@article {bornstein_pickblue_2024,
	title = {PickBlue: Seismic Phase Picking for Ocean Bottom Seismometers With Deep Learning},
	journal = {Earth and Space Science},
	volume = {11},
	number = {1},
	year = {2024},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2023EA003332},
	month = {11/2023},
	pages = {e2023EA003332},
	abstract = {Detecting phase arrivals and pinpointing the arrival times of seismic phases in seismograms is crucial for many seismological analysis workflows. For land station data, machine learning methods have already found widespread adoption. However, deep learning approaches are not yet commonly applied to ocean bottom data due to a lack of appropriate training data and models. Here, we compiled an extensive and labeled ocean bottom seismometer (OBS) data set from 15 deployments in different tectonic settings, comprising \~{}90,000 P and \~{}63,000 S manual picks from 13,190 events and 355 stations. We propose PickBlue, an adaptation of the two popular deep learning networks EQTransformer and PhaseNet. PickBlue joint processes three seismometer recordings in conjunction with a hydrophone component and is trained with the waveforms in the new database. The performance is enhanced by employing transfer learning, where initial weights are derived from models trained with land earthquake data. PickBlue significantly outperforms neural networks trained with land stations and models trained without hydrophone data. The model achieves a mean absolute deviation of 0.05 s for P-waves and 0.12 s for S-waves, and we apply the picker on the Hikurangi Ocean Bottom Tremor and Slow Slip OBS deployment offshore New Zealand. We integrate our data set and trained models into SeisBench to enable an easy and direct application in future deployments.},
	keywords = {machine learning, OBS seismicity database, ocean bottom seismometer, onset determination, phase picking},
	issn = {2333-5084},
	doi = {10.1029/2023EA003332},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2023EA003332},
	author = {Bornstein, T. and Lange, D. and M{\"u}nchmeyer, J. and Woollam, J. and Rietbrock, A. and Barcheck, G. and Grevemeyer, I. and Tilmann, F.}
}
@article {lindner_bayesian_2023,
	title = {Bayesian regional moment tensor from ocean bottom seismograms recorded in the Lesser Antilles: implications for regional stress field},
	journal = {Geophysical Journal International},
	volume = {233},
	number = {2},
	year = {2023},
	month = {12/2022},
	pages = {1036{\textendash}1054},
	abstract = {Seismic activity in the Lesser Antilles (LA) is characterized by strong regional variability along the arc reflecting the complex subduction setting and history. Although routine seismicity monitoring can rely on an increasing number of island stations, the island-arc setting means that high-resolution monitoring and detailed studies of fault structures require a network of ocean bottom seismometers (OBS). As part of the 2016{\textendash}2017 Volatile recycling at the Lesser Antilles arc (VoiLA) project, we deployed 34 OBS stations in the forearc and backarc. During the deployment time, 381 events were recorded within the subduction zone. In this paper, we perform full-waveform regional moment tensor (RMT) inversions, to gain insight into the stress distribution along the arc and at depth. We developed a novel inversion approach, AmΦB{\textemdash}{\textquoteleft}Amphibious Bayesian{\textquoteright}, taking into account uncertainties associated with OBS deployments. Particularly, the orientation of horizontal components (alignment uncertainty) and the high noise level on them due to ocean microseisms are accounted for using AmΦB. The inversion is conducted using a direct, uniform importance sampling of the fault parameters within a multidimensional tree structure: the uniXtree-sampling algorithm. We show that the alignment of the horizontal OBS components, particularly in high noise level marine environments, influences the obtained source mechanism when using standard least-squares (L2) RMT inversion schemes, resulting in systematic errors in the recovered focal mechanisms including high artificial compensated linear vector dipole (CLVD) contributions. Our Bayesian formulation in AmΦB reduces these CLVD components by nearly 60~per~cent and the aberration of the focal geometry as measured by the Kagan angle by around 40~per~cent relative to a standard L2 inversion. Subsequently, we use AmΦB-RMT to obtain 45 (Mw \&gt; 3.8) regional MT solutions, out of which 39 are new to any existing database. Combining our new results with existing solutions, we subsequently analyse a total of 151 solutions in a focal mechanism classification (FMC) diagram and map them to the regional tectonic setting. We also use our newly compiled RMT database to perform stress tensor inversions along the LA subduction zone. On the plate interface, we observe the typical compressional stress regime of a subduction zone and find evidence for upper-plate strike slip and normal fault behaviour in the north that becomes a near arc-perpendicular extensional stress regime towards the south. A dominant slab perpendicular extensional stress regime is found in the slab at 100{\textendash}200~km beneath the central part of the arc. We interpret this stress condition to be a result of slab pull varying along the arc due to partial slab detachment along previously hypothesized lateral slab tear near Grenada, at the southern end of the LA arc, leading to reactivation of pre-existing structures around the subducted Proto-Caribbean ridge.},
	issn = {0956-540X},
	doi = {10.1093/gji/ggac494},
	url = {https://doi.org/10.1093/gji/ggac494},
	author = {Lindner, Mike and Rietbrock, Andreas and Bie, Lidong and Goes, Saskia and Collier, Jenny and Rychert, Catherine and Harmon, Nicholas and Hicks, Stephen P and Henstock, Tim and the VoiLA working group}
}
@article {morton_cascadia_2023,
	title = {Cascadia Subduction Zone Fault Heterogeneities From Newly Detected Small Magnitude Earthquakes},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {128},
	number = {6},
	year = {2023},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2023JB026607},
	month = {05/2023},
	pages = {e2023JB026607},
	abstract = {The Cascadia subduction zone (CSZ) is known to host M9 megathrust ruptures; however, no such event has occurred in historical observation. The distribution and characteristics of small- to moderate-sized earthquakes can be used to determine the behavior of the megathrust fault but are notably absent offshore the CSZ due to the distance from onshore seismometers. We use automated subspace detection coupled with an onshore-offshore seismic deployment to find small-magnitude earthquakes in the offshore seismogenic zone and analyze their locations in the context of interseismic locking and seismogenic zone extent. We detected and located 5,282 earthquakes, 4,096 of which had been previously undetected. We find that the downdip extent of the seismogenic zone as defined by interplate seismicity agrees with the 20\% locking contour of the Schmalzle et al. (2014, https://doi.org/10.1002/2013GC005172) geodetic model and extends deeper than predicted by previous thermal models. We cannot determine the updip extent of the seismogenic zone; this may be due to a lack of templates for detection in the updip source area, stress shadows updip of asperity loading, and/or strong locking to the trench. We present a map of possible asperities determined by the small earthquakes in this study. Our asperity locations and extents show some, but not complete, agreement with the asperities modeled from the 1700 M9 rupture and geodetic locking models, and good agreement with the paleo-rupture extents determined from offshore turbidites and forearc basin-based asperity estimates. This highlights the need of continued offshore observations over time, and to elucidate fine-scale variation in locking.},
	issn = {2169-9356},
	doi = {10.1029/2023JB026607},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2023JB026607},
	author = {Morton, Emily A. and Bilek, Susan L. and Rowe, Charlotte A.}
}
@article {canales_casie21-obs_2023,
	title = {CASIE21-OBS: An Open-Access, OBS Controlled-Source Seismic Data Set for Investigating the Structure and Properties of the Cascadia Accretionary Wedge and the Downgoing Explorer-Juan de Fuca-Gorda Plate System},
	journal = {Seismological Research Letters},
	volume = {94},
	year = {2023},
	note = {Publisher: Seismological Society of America (SSA)},
	month = {07/2023},
	pages = {2093{\textendash}2109},
	abstract = {Geological processes at subduction zones and their associated geohazards (e.g., megathrust earthquakes, submarine landslides, tsunamis, and arc volcanism) are, to a large extent, controlled by the structure, physical properties and fluid content of the subducting plate, the accreted sediments, and the overriding plate. In these settings, modern seismic modeling and imaging techniques based on controlled-source, multicomponent ocean-bottom seismometer (OBS) data are some of the best tools available for determining the subseafloor elastic properties, which can be linked to the aforementioned properties. Here, we present CASIE21-OBS, a controlled-source marine wide-angle OBS data set recently collected across the Cascadia convergent margin as part of the larger CAscadia Seismic Imaging Experiment 2021 (CASIE21). The main component of CASIE21 is a long-offset multichannel seismic (MCS) survey of the Cascadia margin conducted in June{\textendash}July 2021 onboard R/V M.G. Langseth (cruise MGL2104) aiming to characterize the incoming plate, the plate interface geometry and properties, and the overlying sediment stratigraphy and physical properties. CASIE21-OBS was conducted during R/V M.G. Langseth cruise MGL2103 (May 2021) and R/V Oceanus cruise OC2106A (June{\textendash}July 2021). It consisted of 63 short-period four-component OBSs deployed at a total 120 stations along 10 across-trench profiles extending from \~{}50 km seaward of the deformation front to the continental shelf, and from offshore northern Vancouver Island to offshore southern Oregon. The OBSs recorded the airgun signals of the CASIE21-MCS survey as well as natural seismicity occurring during the deployment period (24 May 2021 19:00 UTC{\textendash}9 July 2021 09:00 UTC). The OBS data are archived and available at the Incorporated Research Institutions for Seismology Data Management Center under network code YR_2021 for continuous time series (miniSEED) and identifier 21-008 for assembled data set (SEG-Y).},
	keywords = {3706 Geophysics},
	issn = {0895-0695},
	doi = {10.1785/0220230010},
	author = {Canales, Juan Pablo and Miller, Nathaniel C. and Baldwin, Wayne and Carbotte, Suzanne M. and Han, Shuoshuo and Boston, Brian and Jian, Hanchao and Collins, John and Lizarralde, Dan}
}
@article {banerjee_hydrovolcanic_2023,
	title = {Hydrovolcanic Explosions at the Lava Ocean Entry of the 2018 Kilauea Eruption Recorded by Ocean-Bottom Seismometers},
	journal = {Seismological Research Letters},
	year = {2023},
	month = {mar},
	abstract = {From the beginning of May 2018, the Kilauea Volcano on the island of Hawaii experienced its largest eruption in 200~yr followed by a period of unrest for months. Because hot molten lava entered the ocean from the ocean-entry point near the lower East Rift Zone, the lava{\textendash}water interaction led to explosions. Some explosions were near the water surface and ejected fragments of lava, also known as lava bombs. In the early morning on 16 July 2018, one of those lava bombs, which was almost the size of a basketball, hit a sightseeing boat and injured 23 people. In this study, we analyzed the hydrophone data recorded from July to mid-September by ocean-bottom seismometers (OBSs) deployed offshore near the ocean entry point to identify and locate the hydroacoustic signals of the lava{\textendash}water explosions. Acoustic signals of hydrovolcanic explosions are characterized by a short duration (less than a few seconds) and a broad frequency range (at least up to 100~Hz). To automate event detection, a short-term average versus long-term average method was applied to the complete dataset. Approximately 4300 events were detected and located near the coastline and further used to prepare a catalog. The distribution of the lava{\textendash}water explosions is consistent with the pattern of the offshore lava delta formed during the 2018 eruption. Identifying such hydroacoustic signals recorded by OBSs may provide new avenues of research using various seismoacoustic events associated with volcanic eruptions.},
	issn = {0895-0695},
	doi = {10.1785/0220220195},
	url = {https://doi.org/10.1785/0220220195},
	author = {Banerjee, Puja and Shen, Yang}
}
@article {schlaphorst_local_2023,
	title = {Local seismicity around the Chain Transform Fault at the Mid-Atlantic Ridge from OBS observations},
	journal = {Geophysical Journal International},
	volume = {234},
	number = {2},
	year = {2023},
	note = {Publisher: Oxford University Press (OUP)},
	month = {08/2023},
	pages = {1111{\textendash}1124},
	abstract = {Seismicity along transform faults provides important constraints for our understanding of the factors that control earthquake ruptures. Oceanic transform faults are particularly informative due to their relatively simple structure in comparison to their continental counterparts. The seismicity of several fast-moving transform faults has been investigated by local networks, but as of today there been few studies of transform faults in slow spreading ridges. Here, we present the first local seismicity catalogue based on event data recorded by a temporary broad-band network of 39 ocean{\textendash}bottom seismometers located around the slow-moving Chain Transform Fault (CTF) along the Mid-Atlantic Ridge (MAR) from 2016 to 2017 March. We locate 972 events in the area by simultaneously inverting for a 1-D velocity model informed by the event P- and S-arrival times. We refine the depths and focal mechanisms of the larger events using deviatoric moment tensor inversion. Most of the earthquakes are located along the CTF (700) and Romanche transform fault (94) and the MAR (155); a smaller number (23) can be observed on the continuing fracture zones or in intraplate locations. The ridge events are characterized by normal faulting and most of the transform events are characterized by strike-slip faulting, but with several reverse mechanisms that are likely related to transpressional stresses in the region. CTF events range in magnitude from 1.1 to 5.6 with a magnitude of completeness around 2.3. Along the CTF we calculate a b-value of 0.81 {\textpm} 0.09. The event depths are mostly shallower than 15 km below sea level (523), but a small number of high-quality earthquakes (16) are located deeper, with some (8) located deeper than the brittle-ductile transition as predicted by the 600 {\textdegree}C-isotherm from a simple thermal model. The deeper events could be explained by the control of sea water infiltration on the brittle failure limit.},
	keywords = {3706 Geophysics},
	issn = {0956-540X},
	doi = {10.1093/gji/ggad124},
	author = {Schlaphorst, David and Rychert, Catherine A. and Harmon, Nicholas and Hicks, Stephen P. and Bogiatzis, Petros and Kendall, J-Michael and Abercrombie, Rachel E.}
}
@article {boyce_new_2023,
	title = {A new P-wave Tomographic Model (CAP22) for North America: Implications for the Subduction and Cratonic Metasomatic Modification History of Western Canada and Alaska},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {128},
	number = {3},
	year = {2023},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2022JB025745},
	pages = {e2022JB025745},
	abstract = {Our understanding of the present-day state and evolution of the Canadian and Alaskan mantle is hindered by a lack of absolute P-wavespeed constraints that provide complementary sensitivity to composition in conjunction with existing S-wavespeed models. Consequently, cratonic modification, orogenic history of western North America and complexities within the Alaskan Proto-Pacific subduction system remain enigmatic. One challenge concerns the difficulties in extracting absolute arrival-time measurements from often-noisy data recorded by temporary seismograph networks required to fill gaps in continental and global databases. Using the Absolute Arrival-time Recovery Method (AARM), we extract > 180,000 new absolute arrival-time residuals from seismograph stations across Canada and Alaska and combine these data with USArray and global arrival-time data from the contiguous US and Alaska. We develop a new absolute P-wavespeed tomographic model, CAP22, spanning North America that significantly improves resolution in Canada and Alaska over previous models. Slow wavespeeds below the Canadian Cordillera sharply abut fast wavespeeds of the continental interior at the Rocky Mountain Trench in southwest Canada. Slow wavespeeds below the Mackenzie Mountains continue farther inland in northwest Canada, indicating Proterozoic-Archean metasomatism of the Slave craton. Inherited tectonic lineaments colocated with this north-south wavespeed boundary suggest that both the crust and mantle may control Cordilleran orogenic processes. In Alaska, fast upper mantle wavespeeds below the Wrangell Volcanic Field favor a conventional subduction related mechanism for volcanism. Finally, seismic evidence for the subducted Kula and Yukon slabs indicate tectonic reconstructions of western North America may require revision.},
	keywords = {Alaskan Subduction Zone, body wave tomography, Cordilleran Orogenesis, North America, Slave Craton},
	issn = {2169-9356},
	doi = {10.1029/2022JB025745},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2022JB025745},
	author = {Boyce, A. and Liddell, M. V. and Pugh, S. and Brown, J. and McMurchie, E. and Parsons, A. and Est{\`e}ve, C. and Burdick, S. and Darbyshire, F. A. and Cottaar, S. and Bastow, I. D. and Schaeffer, A. J. and Audet, P. and Schutt, D. L. and Aster, R. C.}
}
@article {dai_novel_2023,
	title = {A Novel Method to Estimate Orientations of an Ocean-Bottom Seismometer Array for Accurate Measurement of Waveform Phases and Amplitudes},
	journal = {Seismological Research Letters},
	volume = {94},
	number = {4},
	year = {2023},
	pages = {1936{\textendash}1947},
	abstract = {The misorientation of three-component seismometers restricts the application of relevant seismic experiments such as ocean-bottom seismometer (OBS) arrays. Previous orientation determination relied on an assumption that the propagation azimuth of seismic waves follows the great-circle path (GCP) azimuth. This assumption may yield systematic errors in the estimated orientation, particularly when the ray paths are bent laterally due to velocity heterogeneity in the Earth. Here, we develop a new method for unbiasedly estimating the horizontal orientations of seismic sensors and apply this method to the Blanco transform fault OBS experiment. We first retrieve the orientations relative to the propagation azimuths from the recorded Rayleigh and P waveforms, and then determine the geographic north orientations by calculating the propagation azimuths via an Eikonal-equation-based phase-tracking method that theoretically accounts for the effect of ray bending. Synthetics test validates that the phase-tracking method can retrieve unbiased propagation azimuths of seismic waves. The final results derived from Rayleigh- and P-wave polarization analyses with the respective phase-tracked propagation azimuths are more consistent and the orientation errors are smaller, indicating the robustness and accuracy of this method. Comparing the orientations from our phase-tracking method to those from the GCP assumption, the deviation can reach up to 8{\textdegree} between these two techniques in the study region. Subsequently, when orientations of the synthetics modeled from three-dimensional elastic waveform simulation are deviated according to the GCP-predicted orientations, we find nonnegligible bias in the phase and amplitude measurements that could reduce the accuracy and resolution of following inversion, which indicates the significance of our phase-tracking method in accurate orientation of OBS arrays as well as inland seismic experiments.},
	issn = {0895-0695},
	doi = {10.1785/0220220363},
	url = {https://doi.org/10.1785/0220220363},
	author = {Dai, Andy and Bao, Xueyang and Sun, Yao-Chong and Shan, Hao}
}
@article {yang_optimal_2023,
	title = {Optimal stacking of noise cross-correlation functions},
	journal = {Geophysical Journal International},
	volume = {232},
	number = {3},
	year = {2023},
	month = {mar},
	pages = {1600{\textendash}1618},
	abstract = {Cross-correlations of ambient seismic noise are widely used for seismic velocity imaging, monitoring and ground motion analyses. A typical step in analysing noise cross-correlation functions (NCFs) is stacking short-term NCFs over longer time periods to increase the signal quality. Spurious NCFs could contaminate the stack, degrade its quality and limit its use. Many methods have been developed to improve the stacking of coherent waveforms, including earthquake waveforms, receiver functions and NCFs. This study systematically evaluates and compares the performance of eight stacking methods, including arithmetic mean or linear stacking, robust stacking, selective stacking, cluster stacking, phase-weighted stacking, time{\textendash}frequency phase-weighted stacking, Nth-root stacking and averaging after applying an adaptive covariance filter. Our results demonstrate that, in most cases, all methods can retrieve clear ballistic or first arrivals. However, they yield significant differences in preserving the phase and amplitude information. This study provides a practical guide for choosing the optimal stacking method for specific research applications in ambient noise seismology. We evaluate the performance using multiple onshore and offshore seismic arrays in the Pacific Northwest region. We compare these stacking methods for NCFs calculated from raw ambient noise (referred to as Raw NCFs) and from ambient noise normalized using a one-bit clipping time normalization method (referred to as One-bit NCFs). We evaluate six metrics, including signal-to-noise ratios, phase dispersion images, convergence rate, temporal changes in the ballistic and coda waves, relative amplitude decays with distance and computational time. We show that robust stacking is the best choice for all applications (velocity tomography, monitoring and attenuation studies) using Raw NCFs. For applications using One-bit NCFs, all methods but phase-weighted and Nth-root stacking are good choices for seismic velocity tomography. Linear, robust and selective stacking methods are all equally appropriate choices when using One-bit NCFs for monitoring applications. For applications relying on accurate relative amplitudes, the linear, robust, selective and cluster stacking methods all perform well with One-bit NCFs. The evaluations in this study can be generalized to a broad range of time-series analysis that utilizes data coherence to perform ensemble stacking. Another contribution of this study is the accompanying open-source software package, StackMaster, which can be used for general purposes of time-series stacking.},
	issn = {0956-540X},
	doi = {10.1093/gji/ggac410},
	url = {https://doi.org/10.1093/gji/ggac410},
	author = {Yang, Xiaotao and Bryan, Jared and Okubo, Kurama and Jiang, Chengxin and Clements, Timothy and Denolle, Marine A}
}
@article {webb_optimizing_2023,
	title = {Optimizing Ocean Bottom Seismometers for Shallow Water Using Shielding and Horizontal Pressure Gradient Data},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {128},
	number = {8},
	year = {2023},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2023JB026356},
	pages = {e2023JB026356},
	abstract = {We show large {\textquotedblleft}shields{\textquotedblright} can significantly reduce horizontal component noise levels for ocean bottom seismometers by shielding the seismic sensors from shaking due to ocean currents. However, at short period (<1 s) some noise from vibration or rocking of the shield under current can partly couple through the ground causing peaks in the noise spectra. Deformation of the seafloor under ocean wave loading ({\textquotedblleft}compliance{\textquotedblright}) raises noise levels at long period (>5 s) for both vertical and horizontal components at shallow water sites. Pressure gauge data is now routinely used to predict and remove this source of noise on vertical component data. We have developed horizontal pressure gradient (HPG) gauges to measure and remove this source of noise from horizontal component data. The combination of HPG data and shielding enables low noise long period seismic observations at otherwise very noisy shallow seafloor sites.},
	keywords = {instrumentation, seafloor, seismology},
	issn = {2169-9356},
	doi = {10.1029/2023JB026356},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2023JB026356},
	author = {Webb, Spahr C. and Barclay, Andrew H.}
}
@article {262,
	title = {Slab to back-arc to arc: Fluid and melt pathways through the mantle wedge beneath the Lesser Antilles},
	journal = {Science Advances},
	volume = {9},
	year = {2023},
	month = {02/2023},
	pages = {eadd2143},
	abstract = {Volatiles expelled from subducted plates promote melting of the overlying warm mantle, feeding arc volcanism. However, debates continue over the factors controlling melt generation and transport, and how these determine the placement of volcanoes. To broaden our synoptic view of these fundamental mantle wedge processes, we image seismic attenuation beneath the Lesser Antilles arc, an end-member system that slowly subducts old, tectonized lithosphere. Punctuated anomalies with high ratios of bulk-to-shear attenuation (Qκ-1/Qμ-1 > 0.6) and VP/VS (>1.83) lie 40 km above the slab, representing expelled fluids that are retained in a cold boundary layer, transporting fluids toward the back-arc. The strongest attenuation (1000/QS ~ 20), characterizing melt in warm mantle, lies beneath the back-arc, revealing how back-arc mantle feeds arc volcanoes. Melt ponds under the upper plate and percolates toward the arc along structures from earlier back-arc spreading, demonstrating how slab dehydration, upper-plate properties, past tectonics, and resulting melt pathways collectively condition volcanism.},
	keywords = {3706 Geophysics},
	issn = {2375-2548},
	doi = {10.1126/sciadv.add2143},
	url = {https://www.science.org/doi/10.1126/sciadv.add2143},
	author = {Hicks, SP and Bie, L and Rychert, CA and Harmon, N and Goes, S and Rietbrock, A and Wei, SS and Collier, JS and Henstock, TJ and Lynch, L and Prytulak, J and Macpherson, CG and Schlaphorst, D and Wilkinson, JJ and Blundy, JD and Cooper, GF and Davy, RG and Kendall, J-M and VOILA WORKING GROUP}
}
@article {janiszewski_broad-band_2023,
	title = {Broad-band ocean bottom seismometer noise properties},
	journal = {Geophysical Journal International},
	volume = {233},
	number = {1},
	year = {2022},
	month = {11/2022},
	pages = {297{\textendash}315},
	abstract = {We present a new compilation and analysis of broad-band ocean bottom seismometer noise properties from 15 yr of seismic deployments. We compile a comprehensive data set of representative four-component (seismometer and pressure gauge) noise spectra and cross-spectral properties (coherence, phase and admittance) for 551 unique stations spanning 18 U.S.-led experiments. This is matched with a comprehensive compilation of metadata parameters related to instrumentation and environmental properties for each station. We systematically investigate the similarity of noise spectra by grouping them according to these metadata parameters to determine which factors are the most important in determining noise characteristics. We find evidence for improvements in similarity of noise properties when grouped across parameters, with groupings by seismometer type and deployment water depth yielding the most significant and interpretable results. Instrument design, that is the entire deployed package, also plays an important role, although it strongly covaries with seismometer and water depth. We assess the presence of traditional sources of tilt, compliance, and microseismic noise to characterize their relative role across a variety of commonly used seismic frequency bands. We find that the presence of tilt noise is primarily dependent on the type of seismometer used (covariant with a particular subset of instrument design), that compliance noise follows anticipated relationships with water depth, and that shallow, oceanic shelf environments have systematically different microseism noise properties (which are, in turn, different from instruments deployed in shallow lake environments). These observations have important implications for the viability of commonly used seismic analysis techniques. Finally, we compare spectra and coherences before and after vertical channel tilt and compliance noise removal to evaluate the efficacy and limitations of these now standard processing techniques. These findings may assist in future experiment planning and instrument development, and our newly compiled noise data set serves as a building block for more targeted future investigations by the marine seismology community.},
	issn = {0956-540X},
	doi = {10.1093/gji/ggac450},
	url = {https://doi.org/10.1093/gji/ggac450},
	author = {Janiszewski, Helen A and Eilon, Z and Russell, J B and Brunsvik, B and Gaherty, J B and Mosher, S G and Hawley, W B and Coats, S}
}
@article {ruppert_enhanced_2022,
	title = {Enhanced Regional Earthquake Catalog with Alaska Amphibious Community Seismic Experiment Data},
	journal = {Seismological Research Letters},
	volume = {94},
	number = {1},
	year = {2022},
	pages = {522{\textendash}530},
	abstract = {The Alaska Amphibious Community Seismic Experiment (AACSE) comprised 75 ocean-bottom seismometers and 30 land stations and covered about 650~km along the segment of the subduction zone that includes Kodiak Island, the Alaska Peninsula and the Shumagin Islands between May 2018 and September 2019. This unprecedented onshore-offshore dataset provided an opportunity to compile a greatly enhanced earthquake catalog for the region by both increasing the number of detected earthquakes and improving the accuracy of their source parameters. We use all available regional and AACSE campaign seismic data to compile an earthquake catalog for the region between Kodiak and the Shumagin Islands including the Alaska Peninsula (51{\textdegree}~N{\textendash}59{\textdegree}~N, 148{\textdegree}~W{\textendash}163{\textdegree}~W). We apply the same processing and reporting standards to additional picks and events as the Alaska Earthquake Center currently uses for compilation of the authoritative regional earthquake catalog. Over 7200 events (both newly detected and previously reported) have been processed with AACSE data. We added about 30\% more events, 60\% more phase picks, lowered the magnitude of completeness by about 0.2 on average across the region, and improved location errors. All data have been published in public data archives. In addition, we test the machine-learning earthquake detection and picking algorithm EarthquakeTransformer (EQT) on the AACSE seismic dataset, comparing EQT-determined P and S picks with the new catalog. EQT is entirely trained on land data, whereas AACSE is amphibious. Overall, EQT finds 59\% of P and 63\% of S arrivals in the catalog within 300~km epicentral distance. The percent of catalog picks detected by EQT varies inversely with earthquake epicentral distance, and EQT performs particularly poorly on data from earthquakes recorded by instruments in the outer rise.},
	issn = {0895-0695},
	doi = {10.1785/0220220226},
	url = {https://doi.org/10.1785/0220220226},
	author = {Ruppert, Natalia A. and Barcheck, Grace and Abers, Geoffrey A.}
}
@article {christeson_seismic_2022,
	title = {Seismic evidence for magmatic underplating along the Kodiak-Bowie Seamount Chain, Gulf of Alaska},
	journal = {Tectonophysics},
	volume = {845},
	year = {2022},
	month = {11/2022},
	pages = {229639},
	abstract = {Oceanic crust formed at mid-ocean ridges may be later modified by off-ridge magmatism forming seamounts, guyots, and islands. We investigate processes associated with seamount formation in the Gulf of Alaska Seamount Province using two coincident seismic reflection/wide-angle profiles. A north-south profile crosses the Kodiak-Bowie Seamount Chain and Aja fracture zone (FZ), and an orthogonal east-west profile is located about 90~km south of the seamount chain over Pacific plate oceanic crust. Structure along the profile away from the seamount chain is consistent with typical oceanic crust. Crust in our study region is thinnest (about 5.6~km) at the Aja FZ. Unlike observations from active transform faults, no low-velocity anomaly is observed at the Aja FZ suggesting that the crustal velocities have recovered to normal values through crack closure and crack healing. Higher lower crustal velocities (\~{}7.3 and~>~7.5~km/s) and thicker crust (\~{}8.5 and~\~{}7.0~km) are observed near the Pratt and Durgin Seamounts and at the intersection of the Kodiak-Bowie Seamount Chain linear trend, respectively. These observations are attributed to magmatic underplating associated with seamount province magmatism. Lithospheric thickness variations across the Aja FZ may form a barrier or impediment to magmatic flow. The thickest crust (8.5~km) along our two profiles is located on the younger side of the FZ, and we suggest that the majority of magmatism jumped south of the Aja FZ when thinner lithosphere was encountered by the Bowie hot spot. The crustal structure near the Kodiak-Bowie Seamount Chain is most similar to that of other seamounts and guyots that formed on similarly young lithosphere (8{\textendash}12~Ma). Our results suggest that lithospheric thickness at the time of hot spot interaction has a large control on magmatic underplating at seamounts and seamount provinces.},
	keywords = {Fracture zone, Magmatic underplating, Seamount},
	issn = {0040-1951},
	doi = {10.1016/j.tecto.2022.229639},
	url = {https://www.sciencedirect.com/science/article/pii/S0040195122004334},
	author = {Christeson, Gail L. and Gulick, Sean P. S. and Walton, Maureen A. L. and Barth, Ginger A.}
}
@article {xu_seismic_2022,
	title = {A Seismic Tomography, Gravity, and Flexure Study of the Crust and Upper Mantle Structure of the Emperor Seamounts at Jimmu Guyot},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {127},
	number = {6},
	year = {2022},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2021JB023241},
	month = {05/2022},
	pages = {e2021JB023241},
	abstract = {The intraplate Hawaiian-Emperor Seamount Chain has long been considered a hotspot track generated by the motion of the Pacific plate over a deep mantle plume, and an ideal feature therefore for studies of volcanic structure, magma supply, plume-crust interaction, flexural loading, and upper mantle rheology. Despite their importance as a major component of the chain, the Emperor Seamounts have been relatively little studied. In this paper, we present the results of an active-source wide-angle reflection and refraction experiment conducted along an ocean-bottom-seismograph (OBS) line oriented perpendicular to the seamount chain, crossing Jimmu guyot. The tomographic P wave velocity model, using \~{}20,000 travel times from 26 OBSs, suggests that there is a high-velocity (>6.0 km/s) intrusive core within the edifice, and the extrusive-to-intrusive ratio is estimated to be \~{}2.5, indicating that Jimmu was built mainly by extrusive processes. The total volume for magmatic material above the top of the oceanic crust is \~{}5.3 {\texttimes} 104 km3, and the related volume flux is \~{}0.96 m3/s during the formation of Jimmu. Under volcanic loading, the \~{}5.3-km-thick oceanic crust is depressed by \~{}3.8 km over a broad region. Using the standard relationships between Vp and density, the velocity model is verified by gravity modeling, and plate flexure modeling indicates an effective elastic thickness (Te) of \~{}14 km. Finally, we find no evidence for large-scale magmatic underplating beneath the pre-existing crust.},
	keywords = {Emperor Seamounts, gravity modeling, oceanic crust, plate flexure, seamount structure, seismic tomography},
	issn = {2169-9356},
	doi = {10.1029/2021JB023241},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2021JB023241},
	author = {Xu, C. and Dunn, R. A. and Watts, A. B. and Shillington, D. J. and Grevemeyer, I. and G{\'o}mez de la Pe{\~n}a, L. and Boston, B. B.}
}
@article {boulahanis_structure_2022,
	title = {Structure and Evolution of Northern Juan de Fuca Crust and Uppermost Mantle Over the Last 8 Ma From an Active-Source Seismic Tomography Study},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {127},
	number = {9},
	year = {2022},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2022JB023987},
	month = {08/2022},
	pages = {e2022JB023987},
	abstract = {We present results from a two-dimensional wide-angle controlled source seismic transect designed to characterize the velocity structure of the oceanic crust and uppermost mantle spanning the northern Juan de Fuca (JdF) plate from near Endeavor ridge to the Cascadia margin. Reflection and refraction travel time inversion is used to derive a tomographic Vp model of sediments, crust, and upper mantle. Velocity model results are compared to baseline reference Vp values for unaltered crustal and upper mantle rocks at temperatures assuming plate cooling. Effective medium theory is used to infer the degree of hydration of the crust and mantle. Results indicate a somewhat fractured and hydrated upper crust (<=2.5 wt\% water), a near dry lower crust (<=0.7 wt\%) and upper mantle (<=0.5 wt\%) west of the deformation front, and an \~{}75 km wide region of modestly lower velocity in the mid-plate. Comparison with prior results from a complementary transect offshore Oregon indicates significant differences in Vp of the upper crust, with lower Vp-inferred porosity along most of the Washington transects that may reflect different extents of fault-related alteration and sediment burial histories. Approaching the deformation front, Washington transect Vp structure indicates dryer conditions than offshore Oregon, consistent with differences in extent of subduction bend faulting found in reflection imaging studies. On both transects, quasi-abrupt changes in plate properties at ages of 8, 6, and 3.4/4 Ma are found. Distinct crustal accretion modes are recognized, aligning with changes in JdF plate motion and recent history of Cobb-Eickelberg hotspot influence on crustal accretion at the JdF ridge.},
	issn = {2169-9356},
	doi = {10.1029/2022JB023987},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2022JB023987},
	author = {Boulahanis, Bridgit and Carbotte, Suzanne M. and Canales, Juan Pablo and Han, Shuoshuo and Nedimovi{\'c}, Mladen R.}
}
@article {wang_temporal_2022,
	title = {Temporal velocity variations in the northern Hikurangi margin and the relation to slow slip},
	journal = {Earth and Planetary Science Letters},
	volume = {584},
	year = {2022},
	month = {04/2022},
	pages = {117443},
	abstract = {Slow slip events (SSE) have been studied in increasing detail over the last 20 years, improving our understanding of subduction zone processes. Although the relationship between SSEs and the physical properties of their surrounding materials is still not well-understood, the northern Hikurangi margin in New Zealand is the site of relatively shallow (<10 km deep), frequent SSEs, providing excellent opportunities for near-field investigations. From September to October 2014, an SSE occurred with more than 250 mm slip, and was recorded successfully by the Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip (HOBITSS) deployment. This study applies scattered wave interferometry to ambient noise data acquired by nine HOBITSS ocean bottom seismometers (OBS) to study the seismic velocity variations related to the SSE. Single station cross-component correlations are computed within a period band that focuses on the upper plate in our study region. The average velocity variations display a decrease on the order of 0.05\% during the SSE, followed by an increase of similar magnitude afterwards. We suggest two possibilities. The first possibility, which has been suggested by other seismological observations, is that the SSE causes a low-permeability seal on the plate boundary to break. The break allows fluid to migrate into the upper plate, causing a seismic velocity decrease during the SSE because of increased pore fluid volume in the upper plate. Under this model, after the SSE, the fluids in the upper plate diffuse gradually and the velocity increases again. The second possibility is the velocity changes are related to changes in crustal strain during the slow slip cycle, whereby elastic strain accumulates prior to the SSE, causing contraction and reduction of porosity and therefore increase of velocity above the SSE source (the seismic velocity increases between SSEs). During the SSE the upper plate goes into extension as the elastic strain is released, which results in dilation and a porosity increase (seismic velocity reduction). After the SSE, stress and strain accumulate again, causing a porosity decrease and a velocity increase.},
	keywords = {ambient noise, seismic velocity variations, slow slip event, the Hikurangi subduction zone},
	issn = {0012-821X},
	doi = {10.1016/j.epsl.2022.117443},
	url = {https://www.sciencedirect.com/science/article/pii/S0012821X22000796},
	author = {Wang, Weiwei and Savage, Martha K. and Yates, Alexander and Zal, Hubert J. and Webb, Spahr and Boulton, Carolyn and Warren-Smith, Emily and Madley, Megan and Stern, Tim and Fry, Bill and Mochizuki, Kimihiro and Wallace, Laura}
}
@article {cabieces_upper-lithospheric_2022,
	title = {Upper-lithospheric structure of northeastern Venezuela from joint inversion of surface-wave dispersion and receiver functions},
	journal = {Solid Earth},
	volume = {13},
	number = {11},
	year = {2022},
	note = {Publisher: Copernicus GmbH},
	month = {11/2022},
	pages = {1781{\textendash}1801},
	abstract = {We use 1.5 years of continuous recordings from an amphibious seismic network deployment in the region of northeastern South America and the southeastern Caribbean to study the crustal and uppermost mantle structure through a joint inversion of surface-wave dispersion curves determined from ambient seismic noise and receiver functions. The availability of both ocean bottom seismometers (OBSs) and land stations makes this experiment ideal to determine the best processing methods to extract reliable empirical Green{\textquoteright}s functions (EGFs) and construct a 3D shear velocity model. Results show EGFs with high signal-to-noise ratio for land{\textendash}land, land{\textendash}OBS and OBS{\textendash}OBS paths from a variety of stacking methods. Using the EGF estimates, we measure phase and group velocity dispersion curves for Rayleigh and Love waves. We complement these observations with receiver functions, which allow us to perform an H-k analysis to obtain Moho depth estimates across the study area. The measured dispersion curves and receiver functions are used in a Bayesian joint inversion to retrieve a series of 1D shear-wave velocity models, which are then interpolated to build a 3D model of the region. Our results display clear contrasts in the oceanic region across the border of the San Sebastian{\textendash}El Pilar strike-slip fault system as well as a high-velocity region that corresponds well with the continental craton of southeastern Venezuela. We resolve known geological features in our new model, including the Espino Graben and the Guiana Shield provinces, and provide new information about their crustal structures. Furthermore, we image the difference in the crust beneath the Matur{\'\i}n and Gu{\'a}rico sub-basins.},
	issn = {1869-9510},
	doi = {10.5194/se-13-1781-2022},
	url = {https://se.copernicus.org/articles/13/1781/2022/},
	author = {Cabieces, Roberto and Arnaiz-Rodr{\'\i}guez, Mariano S. and Villase{\~n}or, Antonio and Berg, Elizabeth and Olivar-Casta{\~n}o, Andr{\'e}s and Ventosa, Sergi and Ferreira, Ana M. G.}
}
@article {mark_constraints_2021,
	title = {Constraints on the Depth, Thickness, and Strength of the G Discontinuity in the Central Pacific From S Receiver Functions},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {126},
	number = {4},
	year = {2021},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2019JB019256},
	month = {03/2021},
	pages = {e2019JB019256},
	abstract = {The relative motion of the lithosphere with respect to the asthenosphere implies the existence of a boundary zone that accommodates shear between the rigid plates and flowing mantle. This shear zone is typically referred to as the lithosphere-asthenosphere boundary (LAB). The width of this zone and the mechanisms accommodating shear across it have important implications for coupling between mantle convection and surface plate motion. Seismic observations have provided evidence for several physical mechanisms that might help enable relative plate motion, but how these mechanisms each contribute to the overall accommodation of shear remains unclear. Here we present receiver function constraints on the discontinuity structure of the oceanic upper mantle at the NoMelt site in the central Pacific, where local constraints on shear velocity, anisotropy, conductivity, and attenuation down to \~{}300 km depth provide a comprehensive picture of upper mantle structure. We image a seismic discontinuity with a Vsv decrease of 4.5\% or more over a 0{\textendash}20 km thick gradient layer centered at a depth of \~{}65 km. We associate this feature with the Gutenberg discontinuity (G), and interpret our observation of G as resulting from strain localization across a dehydration boundary based on the good agreement between the discontinuity depth and that of the dry solidus. Transitions in Vsv, azimuthal anisotropy, conductivity, and attenuation observed at roughly similar depths suggest that the G discontinuity represents a region of localized strain within a broader zone accommodating shear between the lithosphere and asthenosphere.},
	issn = {2169-9356},
	doi = {10.1029/2019JB019256},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019JB019256},
	author = {Mark, H. F. and Collins, J. A. and Lizarralde, D. and Hirth, G. and Gaherty, J. B. and Evans, R. L. and Behn, M. D.}
}
@article {brunsvik_mantle_2021,
	title = {Mantle Structure and Flow Across the Continent-Ocean Transition of the Eastern North American Margin: Anisotropic S-Wave Tomography},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {22},
	number = {12},
	year = {2021},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2021GC010084},
	pages = {e2021GC010084},
	abstract = {Little has been seismically imaged through the lithosphere and mantle at rifted margins across the continent-ocean transition. A 2014{\textendash}2015 community seismic experiment deployed broadband seismic instruments across the shoreline of the eastern North American rifted margin. Previous shear-wave splitting along the margin shows several perplexing patterns of anisotropy, and by proxy, mantle flow. Neither margin parallel offshore fast azimuths nor null splitting on the continental coast obviously accord with absolute plate motion, paleo-spreading, or rift-induced anisotropy. Splitting measurements, however, offer no depth constraints on anisotropy. Additionally, mantle structure has not yet been imaged in detail across the continent-ocean transition. We used teleseismic S, SKS, SKKS, and PKS splitting and differential travel times recorded on ocean-bottom seismometers, regional seismic networks, and EarthScope Transportable Array stations to conduct joint isotropic/anisotropic tomography across the margin. The velocity model reveals a transition from fast, thick, continental keel to low velocity, thinned lithosphere eastward. Imaged short wavelength velocity anomalies can be largely explained by edge-driven convection or shear-driven upwelling. We also find that layered anisotropy is prevalent across the margin. The anisotropic fast polarization is parallel to the margin within the asthenosphere. This suggests margin parallel flow beneath the plate. The lower oceanic lithosphere preserves paleo-spreading-parallel anisotropy, while the continental lithosphere has complex anisotropy reflecting several Wilson cycles. These results demonstrate the complex and active nature of a margin which is traditionally considered tectonically inactive.},
	keywords = {anisotropy, continent-ocean transition, eastern North American margin, shear wave splitting, tomography},
	issn = {1525-2027},
	doi = {10.1029/2021GC010084},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2021GC010084},
	author = {Brunsvik, Brennan R. and Eilon, Zachary C. and Lynner, Colton}
}
@article {watts_seismic_2021,
	title = {Seismic Structure, Gravity Anomalies and Flexure Along the Emperor Seamount Chain},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {126},
	number = {3},
	year = {2021},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2020JB021109},
	month = {02/2021},
	pages = {e2020JB021109},
	abstract = {The Hawaiian-Emperor seamount chain in the Pacific Ocean has provided fundamental insights into hotspot generated intraplate volcanism and the long-term strength of oceanic lithosphere. However, only a few seismic experiments to determine crustal and upper mantle structure have been carried out on the Hawaiian Ridge, and no deep imaging has ever been carried out along the Emperor seamounts. Here, we present the results of an active source seismic experiment using 29 Ocean-Bottom Seismometers (OBS) carried out along a strike profile of the seamounts in the region of Jimmu and Suiko guyots. Joint reflection and refraction tomographic inversion of the OBS data show the upper crust is highly heterogeneous with P wave velocities <4{\textendash}5 km s-1, which are attributed to extrusive lavas and clastics. In contrast, the lower crust is remarkably homogeneous with velocities of 6.5{\textendash}7.2 km s-1, which we attribute to oceanic crust and mafic intrusions. Moho is identified by a strong PmP arrival at offsets of 20{\textendash}80 km, yielding depths of 13{\textendash}16 km. The underlying mantle is generally homogeneous with velocities in the range 7.9{\textendash}8.0 km s-1. The crust and mantle velocity structure has been verified by gravity modeling. While top of oceanic crust prior to volcano loading is not recognized as a seismic or gravity discontinuity, flexural modeling reveals a \~{}5.0{\textendash}5.5 km thick preexisting oceanic crust that is overlain by a \~{}8 km thick volcanic edifice. Unlike at the Hawaiian Ridge, we find no evidence of magmatic underplating.},
	keywords = {gravity and isostasy, marine geology \& geophysics, marine seismics, oceanic hotspots and intraplate volcanism, seafloor morphology},
	issn = {2169-9356},
	doi = {10.1029/2020JB021109},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2020JB021109},
	author = {Watts, A. B. and Grevemeyer, I. and Shillington, D. J. and Dunn, R. A. and Boston, B. and G{\'o}mez de la Pe{\~n}a, L.}
}
@article {barcheck_alaska_2020,
	title = {The Alaska Amphibious Community Seismic Experiment},
	journal = {Seismological Research Letters},
	volume = {91},
	number = {6},
	year = {2020},
	month = {08/2020},
	pages = {3054{\textendash}3063},
	abstract = {The Alaska Amphibious Community Seismic Experiment (AACSE) is a shoreline-crossing passive- and active-source seismic experiment that took place from May 2018 through August 2019 along an \~{}700  km long section of the Aleutian subduction zone spanning Kodiak Island and the Alaska Peninsula. The experiment featured 105 broadband seismometers; 30 were deployed onshore, and 75 were deployed offshore in Ocean Bottom Seismometer (OBS) packages. Additional strong-motion instruments were also deployed at six onshore seismic sites. Offshore OBS stretched from the outer rise across the trench to the shelf. OBSs in shallow water (\&lt;262  m depth) were deployed with a trawl-resistant shield, and deeper OBSs were unshielded. Additionally, a number of OBS-mounted strong-motion instruments, differential and absolute pressure gauges, hydrophones, and temperature and salinity sensors were deployed. OBSs were deployed on two cruises of the R/V Sikuliaq in May and July 2018 and retrieved on two cruises aboard the R/V Sikuliaq and R/V Langseth in August{\textendash}September 2019. A complementary 398-instrument nodal seismometer array was deployed on Kodiak Island for four weeks in May{\textendash}June 2019, and an active-source seismic survey on the R/V Langseth was arranged in June 2019 to shoot into the AACSE broadband network and the nodes. Additional underway data from cruises include seafloor bathymetry and sub-bottom profiles, with extra data collected near the rupture zone of the 2018 Mw~7.9 offshore-Kodiak earthquake. The AACSE network was deployed simultaneously with the EarthScope Transportable Array (TA) in Alaska, effectively densifying and extending the TA offshore in the region of the Alaska Peninsula. AACSE is a community experiment, and all data were made available publicly as soon as feasible in appropriate repositories.},
	issn = {0895-0695},
	doi = {10.1785/0220200189},
	url = {https://doi.org/10.1785/0220200189},
	author = {Barcheck, Grace and Abers, Geoffrey A. and Adams, Aubreya N. and B{\'e}cel, Anne and Collins, John and Gaherty, James B. and Haeussler, Peter J. and Li, Zongshan and Moore, Ginevra and Onyango, Evans and Roland, Emily and Sampson, Daniel E. and Schwartz, Susan Y. and Sheehan, Anne F. and Shillington, Donna J. and Shore, Patrick J. and Webb, Spahr and Wiens, Douglas A. and Worthington, Lindsay L.}
}
@article {113,
	title = {Body Wave Tomography of the Cascadia Subduction Zone and Juan de Fuca Plate System: Identifying Challenges and Solutions for Shore-Crossing Data},
	journal = {Geochemistry Geophysics Geosystems},
	volume = {21},
	year = {2020},
	type = {Journal Article},
	abstract = {Recent seismic results from the Cascadia Initiative indicate that heterogeneity in the oceanic asthenosphere affects subduction dynamics. Accurate characterization of the oceanic upper mantle is thus necessary to fully understand subduction processes, including the behavioral segmentation of the megathrust. A key challenge is integrating onshore and offshore datasets, which span large variations in near-surface features that teleseismic body wave tomography is ill-posed to resolve. Here, we perform a series of P and S forward modeling predictions to better understand the relative contribution of elevation, crustal thickness, offshore sedimentation, and near-surface velocity structure to teleseismic delay times. Crustal thickness and elevation variations dominate the signal, contributing \~{}1 s of delay time difference for P-waves (roughly double for S). We test several inversion strategies to account for near-surface features, identifying potential artifacts and causes of imaging errors. Undamped station statics are found to absorb mantle structures and introduce low-velocity artifacts beneath the forearc. Our preferred inversion strategy utilizes a three-dimensional starting model (including elevation) of the upper 50 km and heavily damped station statics, which we find leads to better resolution of mantle structure, particularly at asthenospheric depths. These insights guide inversions of observed delay times from the Cascadia subduction zone and Juan de Fuca plate system. We present a new onshore-offshore S model and an updated P model. Major features are common to both models, including localized subslab low-velocity anomalies, along-strike variations in slab structure, and offshore heterogeneity, while regional differences may reflect changes in Vp/Vs.},
	doi = {10.1029/2020gc009316},
	url = {https://app.dimensions.ai/details/publication/pub.1132665170},
	author = {Bodmer, M. and Toomey, D. R. and VanderBeek, B. and Hooft, E. E. and Byrnes, J. S.}
}
@article {becel_evidence_2020,
	title = {Evidence for a Prolonged Continental Breakup Resulting From Slow Extension Rates at the Eastern North American Volcanic Rifted Margin},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {125},
	number = {9},
	year = {2020},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2020JB020093},
	pages = {e2020JB020093},
	abstract = {When continental rifting is accompanied by localized magmatism under extensional stress, the breakup duration can be short and the continent/ocean transition sharp, as mantle melts are thought to be efficient at heating and weakening the lithosphere. This mode of rifting has been invoked for the Eastern North American Margin (ENAM) based on the existing geophysical data. Here, we present results from multichannel seismic profiles from the ENAM Community Seismic Experiment offshore North Carolina, U.S. Our survey area encompasses both the East Coast Magnetic Anomaly (ECMA) and the Blake Spur Magnetic Anomaly (BSMA), which lies 200-km farther seaward. Our prestack depth-migrated seismic images reveal major changes in the structure of the igneous crust across the BSMA. Between the ECMA and BSMA, we image a proto-oceanic domain of rough, faulted, and thin igneous crust. The roughness of this oceanic crust is similar to modern ultraslow spreading environments which involve the continued presence of a pre-existing lithospheric lid. Seaward of the BSMA the basement is smooth, and the crust is relatively thick, which is typical for Jurassic oceanic crust. Across the BSMA, we image a step up in basement and crustal root, which we interpret to represent complete lithospheric breakup and a transition to steady-state seafloor spreading in agreement with coincident refraction results. Our results would also indicate low extension rates in the final stages of rifting that may have influenced the thermal structure of the lithosphere and could explain the delay for continental breakup. All of these observations show that although continental rifting between eastern North America and northwest Africa was assisted by magmatic activity, it did not lead to rapid localization of extensional strain as previously thought.},
	keywords = {Central Atlantic opening, continental breakup, continental margin, proto-oceanic crust, steady-state seafloor spreading, volcanic rifted margin},
	issn = {2169-9356},
	doi = {10.1029/2020JB020093},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2020JB020093},
	author = {B{\'e}cel, Anne and Davis, Joshua K. and Shuck, Brandon D. and Van Avendonk, Harm J. A. and Gibson, James C.}
}
@article {cooper_variable_2020,
	title = {Variable water input controls evolution of the Lesser Antilles volcanic arc},
	journal = {Nature},
	volume = {582},
	number = {7813},
	year = {2020},
	note = {Number: 7813 Publisher: Nature Publishing Group},
	month = {jun},
	pages = {525{\textendash}529},
	abstract = {Oceanic lithosphere carries volatiles, notably water, into the mantle through subduction at convergent plate boundaries. This subducted water exercises control on the production of magma, earthquakes, formation of continental crust and mineral resources. Identifying different potential fluid sources (sediments, crust and mantle lithosphere) and tracing fluids from their release to the surface has proved challenging1. Atlantic subduction zones are a valuable endmember when studying this deep water cycle because hydration in Atlantic lithosphere, produced by slow spreading, is expected to be highly non-uniform2. Here, as part of a multi-disciplinary project in the Lesser Antilles volcanic arc3, we studied boron trace element and isotopic fingerprints of melt inclusions. These reveal that serpentine{\textemdash}that is, hydrated mantle rather than crust or sediments{\textemdash}is a dominant supplier of subducted water to the central arc. This serpentine is most likely to reside in a set of major fracture zones subducted beneath the central arc over approximately the past ten million years. The current dehydration of these fracture zones coincides with the~current locations of the highest rates of earthquakes and prominent low shear velocities, whereas the preceding history~of~dehydration is consistent with the locations of~higher volcanic productivity and thicker arc crust. These combined geochemical and geophysical data indicate that the structure and hydration of the subducted plate are directly connected to the evolution of the arc and its associated seismic and volcanic hazards.},
	keywords = {Geochemistry, Geodynamics, Geophysics, seismology, Volcanology},
	issn = {1476-4687},
	doi = {10.1038/s41586-020-2407-5},
	url = {https://www.nature.com/articles/s41586-020-2407-5},
	author = {Cooper, George F. and Macpherson, Colin G. and Blundy, Jon D. and Maunder, Benjamin and Allen, Robert W. and Goes, Saskia and Collier, Jenny S. and Bie, Lidong and Harmon, Nicholas and Hicks, Stephen P. and Iveson, Alexander A. and Prytulak, Julie and Rietbrock, Andreas and Rychert, Catherine A. and Davidson, Jon P.}
}
@article {doran_calibration_2019,
	title = {Calibration of Differential Pressure Gauges Through In Situ Testing},
	journal = {Earth and Space Science},
	volume = {6},
	number = {12},
	year = {2019},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2019EA000783},
	pages = {2663{\textendash}2670},
	abstract = {Differential pressure gauges (DPGs) are a standard component of modern broadband ocean-bottom seismometer instruments and have proven useful for observing a wide range of seismic and oceanographic phenomena. However, the response function of the DPG remains poorly known, limiting our ability to recover amplitude and phase information from seafloor pressure signals with high fidelity. The sensitivity and long-period response are difficult to calibrate in the lab, as they are known to vary with temperature and pressure and perhaps between sensors of the same design. We present the results of a field experiment designed to determine empirical response functions in situ by inducing a pre-defined pressure offset on a deployed instrument. The results compare favorably with calibrations estimated independently through post-deployment data analyses. Our study demonstrates that observed response functions can deviate from the nominal response by a factor of two or greater with regards to both the sensitivity and the time constant. Incorporating calibration devices such as those described here into future deployments may prove to be a cost-effective way to improve the accuracy and utility of differential pressure data.},
	issn = {2333-5084},
	doi = {10.1029/2019EA000783},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019EA000783},
	author = {Doran, A.k. and Rapa, M. and Laske, G. and Babcock, J. and McPeak, S.}
}
@article {lynner_eastern_2019,
	title = {The Eastern North American Margin Community Seismic Experiment: An Amphibious Active- and Passive-Source Dataset},
	journal = {Seismological Research Letters},
	volume = {91},
	number = {1},
	year = {2019},
	month = {10/2019},
	pages = {533{\textendash}540},
	abstract = {The eastern North American margin community seismic experiment (ENAM-CSE) was conceived to target the ENAM Geodynamic Processes at Rifting and Subducting Margins (GeoPRISMS) primary site with a suite of both active- and passive-source seismic data that would shed light on the processes associated with rift initiation and evolution. To fully understand the ENAM, it was necessary to acquire a seismic dataset that was both amphibious, spanning the passive margin from the continental interior onto the oceanic portion of the North American plate, and multiresolution, enabling imaging of the sediments, crust, and mantle lithosphere. The ENAM-CSE datasets were collected on- and offshore of North Carolina and Virginia over a series of cruises and land-based deployments between April 2014 and June 2015. The passive-source component of the ENAM-CSE included 30 broadband ocean-bottom seismometers (OBSs) and 3 onshore broadband instruments. The broadband stations were deployed contemporaneously with those of the easternmost EarthScope Transportable Array creating a trans-margin amphibious seismic dataset. The active-source portion of the ENAM-CSE included several components: (1)~two onshore wide-angle seismic profiles where explosive shots were recorded on closely spaced geophones; (2)~four major offshore wide-angle seismic profiles acquired with an airgun source and short-period OBSs (SPOBSs), two of which were extended onland by deployments of short-period seismometers; (3)~marine multichannel seismic (MCS) data acquired along the four lines of SPOBSs and a series of other profiles along and across the margin. During the cruises, magnetic, gravity, and bathymetric data were also collected along all MCS profiles. All of the ENAM-CSE products were made publicly available shortly after acquisition, ensuring unfettered community access to this unique dataset.},
	issn = {0895-0695},
	doi = {10.1785/0220190142},
	url = {https://doi.org/10.1785/0220190142},
	author = {Lynner, Colton and J. A. Van Avendonk, Harm and B{\'e}cel, Anne and Christeson, Gail L. and Dugan, Brandon and Gaherty, James B. and Harder, Steven and Hornbach, Matthew J. and Lizarralde, Daniel and Long, Maureen D. and Magnani, M. Beatrice and Shillington, Donna J. and Aderhold, Kasey and Eilon, Zachary C. and Wagner, Lara S.}
}
@article {Kuna2019,
	title = {Mode of slip and crust{\textendash}mantle interaction at oceanic transform faults},
	journal = {Nature Geoscience},
	volume = {12},
	number = {2},
	year = {2019},
	month = {feb},
	pages = {138{\textendash}142},
	issn = {1752-0894},
	doi = {10.1038/s41561-018-0287-1},
	url = {http://www.nature.com/articles/s41561-018-0287-1},
	author = {Kuna, V{\'a}clav M. and N{\'a}b{\v e}lek, John L. and Braunmiller, Jochen}
}
@article {shuck_role_2019,
	title = {The role of mantle melts in the transition from rifting to seafloor spreading offshore eastern North America},
	journal = {Earth and Planetary Science Letters},
	volume = {525},
	year = {2019},
	month = {nov},
	pages = {115756},
	abstract = {The Eastern North American Margin (ENAM) formed in the early Jurassic (\~{}195 Ma) with the breakup of supercontinent Pangea. This rifting event was accompanied by volcanism along the continental shelf of the eastern United States, giving rise to the East Coast Magnetic Anomaly (ECMA). Numerical models show that magmatic diking can assist rifting by reducing the effective stress required to rupture the lithosphere. Therefore, magma-rich rifts can develop a rapid transition from continental breakup to seafloor spreading. Alternatively, the onset of seafloor spreading may be accompanied by a long period of persistent thermal weakening and erosion of the lithosphere. In this paper we present analyses of active-source wide-angle seismic data collected during the 2014 ENAM Community Seismic Experiment in an area that extends farther offshore than previous seismic surveys along the eastern U.S. Seaward of the ECMA lies a zone of thin oceanic crust with high compressional seismic velocity (up to 7.5 km/s in the lower crust), whereas thicker normal oceanic crust lies \~{}200 km farther offshore along another prominent magnetic anomaly, the Blake Spur Magnetic Anomaly (BSMA). We reconcile our seismic images with a petrologic model to evaluate the mantle melting conditions during the late stages of continental breakup and early seafloor spreading in the Central Atlantic. We propose that the zone of thin crust between the ECMA and BSMA with high seismic velocity is best explained by the presence of a \~{}15{\textendash}20 km thick lithospheric lid at the time of early seafloor spreading, which prevented melting in the shallow mantle. Our analysis suggests that the volcanism that produced the nearshore ECMA did not lead to complete lithospheric breakup of the conjugate North American and African margins. Normal seafloor spreading began at the BSMA under a moderately high mantle potential temperature of \~{}1395{\textendash}1420{\textdegree}C, \~{}25 million years after the initial formation of the volcanic margin. These results imply that stretching, thermal weakening, and rupture of the lithosphere may take millions of years, even in the presence of mantle melts.},
	keywords = {continent-ocean transition, continental rifting, eastern North American margin, mantle melting, oceanic crust, seismic tomography},
	issn = {0012-821X},
	doi = {10.1016/j.epsl.2019.115756},
	url = {https://www.sciencedirect.com/science/article/pii/S0012821X19304480},
	author = {Shuck, Brandon D. and Van Avendonk, Harm J. A. and B{\'e}cel, Anne}
}
@article {stephen_three-dimensional_2019,
	title = {Three-dimensional bottom diffraction in the North Pacific},
	journal = {The Journal of the Acoustical Society of America},
	volume = {146},
	number = {3},
	year = {2019},
	note = {Publisher: Acoustical Society of America},
	pages = {1913{\textendash}1922},
	abstract = {A significant aspect of bottom-interaction in deep water acoustic propagation, from point sources to point receivers, is the diffraction (or scattering) of energy from discrete seafloor locations along repeatable, deterministic paths in three-dimensions. These bottom-diffracted surface-reflected (BDSR) paths were first identified on the North Pacific acoustic laboratory experiment in 2004 (NPAL04) for a diffractor located on the side of a small seamount. On the adjacent deep seafloor, ambient noise and propagation in the ocean sound channel were sufficiently quiet that the BDSRs were the dominant arrival. The ocean bottom seismometer augmentation in the North Pacific (OBSANP) experiment in June{\textendash}July 2013 studied BDSRs at the NPAL04 site in more detail. BDSRs are most readily identified by the arrival time of pulses as a function of range to the receiver for a line of transmissions. The diffraction points for BDSRs occur on the relatively featureless deep seafloor as well as on the sides of small seamounts. Although the NPAL04 and OBSANP experiments had very different geometries the same diffractor location is consistent with observed arrivals in both experiments within the resolution of the analysis. On OBSANP the same location excites BDSRs for 77.5, 155, and 310 Hz transmissions.},
	issn = {0001-4966},
	doi = {10.1121/1.5125427},
	url = {https://asa.scitation.org/doi/full/10.1121/1.5125427},
	author = {Stephen, Ralph A. and Bolmer, S. Thompson and Worcester, Peter F. and Dzieciuch, Matthew A. and Udovydchenkov, Ilya A.}
}
@article {pavlis_unified_2019,
	title = {A unified three-dimensional model of the lithospheric structure at the subduction corner in southeast Alaska: Summary results from STEEP},
	journal = {Geosphere},
	volume = {15},
	number = {2},
	year = {2019},
	month = {jan},
	pages = {382{\textendash}406},
	abstract = {We merge structural results from the ST. Elias Erosion/tectonics Project (STEEP), other studies, and seismicity data to build a comprehensive, three-dimensional model of the lithosphere of the subduction corner in southern Alaska. The model is defined by three surfaces: (1) a top of the subducting lithosphere surface, (2) Moho surfaces, and (3) a base of subducting lithosphere surface. We model the eastern edge of the subducting lithosphere using the southern tip of the Yakutat microplate as an anchor. Kinematic reconstructions using that anchor suggest the modern Fairweather fault is likely inherited from motion of the margin in the 6{\textendash}10 Ma period. We constructed a 4D kinematic model of crustal deformation in the vicinity of Mount St. Elias. We call this model the middlebuster model because the geometry is similar to a two-sided plow with that name. The west side of the plow is the eastern limit of the Aleutian megathrust constructed from the union of constraints from STEEP seismic results and slip models of the 1979 St. Elias earthquake. The east side is inferred from geologic mapping and slip models of the 1899 Yakutat Bay earthquake sequence. The top of the plow is near the Seward Glacier, where previous studies showed near world-record exhumation rates. GPS velocity vectors show a large rotation across the syntaxis at Mount St. Elias. West of the syntaxis, faults inferred from inversion of the GPS data are above the megathrust inferred from seismic imaging. That and other evidence suggest the presence of a wedge of ductile crust that partially decouples the subducting mantle lithosphere from the upper crust in the area near the suture with the Yakutat microplate.},
	issn = {1553-040X},
	doi = {10.1130/GES01488.1},
	url = {https://doi.org/10.1130/GES01488.1},
	author = {Pavlis, Gary L. and Bauer, Mark A. and Elliott, Julie L. and Koons, Peter and Pavlis, Terry L. and Ruppert, Natalia and Ward, Kevin M. and Worthington, Lindsay L.}
}
@article {krischer_automated_2018,
	title = {Automated Large-Scale Full Seismic Waveform Inversion for North America and the North Atlantic},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {123},
	number = {7},
	year = {2018},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2017JB015289},
	pages = {5902{\textendash}5928},
	abstract = {We present a new anisotropic seismic tomography model based on a multiscale full seismic waveform inversion for crustal and upper-mantle structure from the western edge of North America across the North Atlantic and into Europe. The gradient-based inversion strategy utilizes the adjoint state method coupled with an L-BFGS quasi-Newton optimization scheme. To improve the handling of large data quantities in the context of full seismic waveform inversions, we developed a workflow framework automating the procedure across all stages, enabling us to confidently invert for waveforms from 72 events recorded at 7,737 unique stations, resulting in a total of 144,693 raypaths, most of them with three-component recordings. The final model after 20 iterations is able to explain complete waveforms including body as well as surface waves of earthquakes that were not used in the inversion down to periods of around 30 s. The model is complemented by a detailed resolution analysis in the form of 3-D distributions of direction-dependent resolution lengths.},
	keywords = {data management, full-waveform inversion, inverse problems, optimization, seismology, workflow},
	issn = {2169-9356},
	doi = {10.1029/2017JB015289},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2017JB015289},
	author = {Krischer, Lion and Fichtner, Andreas and Boehm, Christian and Igel, Heiner}
}
@article {Bodmer2018,
	title = {Buoyant Asthenosphere Beneath Cascadia Influences Megathrust Segmentation},
	journal = {Geophysical Research Letters},
	volume = {45},
	number = {14},
	year = {2018},
	month = {jul},
	pages = {6954{\textendash}6962},
	issn = {0094-8276},
	doi = {10.1029/2018GL078700},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2018GL078700},
	author = {Bodmer, Miles and Toomey, Douglas R. and Hooft, Emilie E. E. and Schmandt, Brandon}
}
@article {li_connections_2018,
	title = {Connections between subducted sediment, pore-fluid pressure, and earthquake behavior along the Alaska megathrust},
	journal = {Geology},
	volume = {46},
	number = {4},
	year = {2018},
	month = {02/2018},
	pages = {299{\textendash}302},
	abstract = {Variations in pore-fluid pressure along subduction megathrusts are often invoked to explain differences in fault slip behavior between margins. However, many other parameters vary between subduction zones, making it difficult to isolate the causes of elevated pore fluid pressures and their effects on megathrust behavior. Here we show evidence from pre-stack depth migrations of multichannel seismic reflection data along the subduction zone off the Alaska Peninsula for significant, systematic along-strike variations in the thickness, continuity, P-wave velocity, and estimated pore-fluid pressure of the subducting sediment layer that lines the shallow plate interface within 25 km of the trench. These variations appear to correlate with changes in seismicity, locking, and earthquake rupture history. The currently locked and seismically quiet Semidi segment has a continuous, thick (600{\textendash}900 m) subducted sediment layer that is characterized by low seismic velocities and elevated pore pressure (λ* ≈ 0.4{\textendash}0.8). The subducted sediment in the neighboring Shumagin Gap, a region with low geodetic coupling and abundant small earthquakes, is thinner, irregular and has lower pore pressure (λ* \&lt; 0.2{\textendash}0.3). We suggest that the thicker and weakly faulted sediment layer entering the trench at Semidi is associated with a continuous and overpressured sediment layer lining the shallow plate interface, but forms a large coherent asperity as it dewaters and consolidates at greater depths, thus favoring large earthquakes. In contrast, thinner incoming sediment disrupted by outer rise faulting at Shumagin results in a plate interface without elevated pore-fluid pressures, but which is heterogeneous and complex at all depths, contributing to creep and frequent small earthquakes.},
	issn = {0091-7613},
	doi = {10.1130/G39557.1},
	url = {https://doi.org/10.1130/G39557.1},
	author = {Li, Jiyao and Shillington, Donna J. and Saffer, Demian M. and B{\'e}cel, Anne and Nedimovi{\'c}, Mladen R. and Kuehn, Harold and Webb, Spahr C. and Keranen, Katie M. and Abers, Geoffrey A.}
}
@article {morton_newly_2018,
	title = {Newly detected earthquakes in the Cascadia subduction zone linked to seamount subduction and deformed upper plate},
	journal = {Geology},
	volume = {46},
	number = {11},
	year = {2018},
	month = {09/2018},
	pages = {943{\textendash}946},
	abstract = {Data from an amphibious seismic network in Cascadia (northwest North America) provide unique near-source observations to assess the influence of subducting topography on seismicity. Using subspace detection, we detect and locate 222 events in two separate clusters, near a subducted seamount and a possibly accreted seamount. Seismicity in both clusters is largely shallower than the plate interface and exhibits occasional swarm-like behavior. This implies that the seamount is subducting aseismically via weak coupling with the overriding plate, while earthquakes in the upper plate arise from a high degree of fracturing due to seamount interaction, and the accreted seamount induced similar fracturing before off-scraping.},
	issn = {0091-7613},
	doi = {10.1130/G45354.1},
	url = {https://doi.org/10.1130/G45354.1},
	author = {Morton, Emily A. and Bilek, Susan L. and Rowe, Charlotte A.}
}
@article {Ruan2018,
	title = {Shear attenuation beneath the Juan de Fuca plate: Implications for mantle flow and dehydration},
	journal = {Earth and Planetary Science Letters},
	volume = {496},
	year = {2018},
	month = {aug},
	pages = {189{\textendash}197},
	issn = {0012821X},
	doi = {10.1016/j.epsl.2018.05.035},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0012821X18303182},
	author = {Ruan, Youyi and Forsyth, Donald W. and Bell, Samuel W.}
}
@article {moyer_spatial_2018,
	title = {Spatial and Temporal Variations in Earthquake Stress Drop on Gofar Transform Fault, East Pacific Rise: Implications for Fault Strength},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {123},
	number = {9},
	year = {2018},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2018JB015942},
	pages = {7722{\textendash}7740},
	abstract = {On Gofar Transform Fault on the East Pacific Rise, the largest earthquakes (6.0 <= MW <= 6.2) have repeatedly ruptured the same portion of the fault, while intervening fault segments host swarms of microearthquakes. These long-term patterns in earthquake occurrence suggest that heterogeneous fault zone properties control earthquake behavior. Using waveforms from ocean bottom seismometers that recorded seismicity before and after an anticipated 2008 MW 6.0 mainshock, we investigate the role that differences in material properties have on earthquake rupture at Gofar. We determine stress drop for 138 earthquakes (2.3 <= MW <= 4.0) that occurred within and between the rupture areas of large earthquakes. Stress drops are calculated from corner frequencies derived using an empirical Green{\textquoteright}s function spectral ratio method, and seismic moments are obtained by fitting the omega-square source model to the low frequency amplitude of the displacement spectrum. Our analysis yields stress drops from 0.04 to 3.2 MPa with statistically significant spatial variation, including 2 times higher average stress drop in fault segments where large earthquakes also occur compared to fault segments that host earthquake swarms. We find an inverse correlation between stress drop and P wave velocity reduction, which we interpret as the effect of fault zone damage on the ability of the fault to store strain energy that leads to our spatial variations in stress drop. Additionally, we observe lower stress drops following the MW 6.0 mainshock, consistent with increased damage and decreased fault strength after a large earthquake.},
	keywords = {earthquake stress drop, earthquake swarms, fault zone damage, oceanic transform faults, rupture dynamics, seismic coupling},
	issn = {2169-9356},
	doi = {10.1029/2018JB015942},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2018JB015942},
	author = {Moyer, Pamela A. and Boettcher, Margaret S. and McGuire, Jeffery J. and Collins, John A.}
}
@article {Zietlow2018,
	title = {Teleseismic S-wave tomography of South Island, New Zealand upper mantle},
	journal = {Geosphere},
	volume = {14},
	number = {3},
	year = {2018},
	month = {jun},
	pages = {1343{\textendash}1364},
	issn = {1553-040X},
	doi = {10.1130/GES01591.1},
	url = {https://pubs.geoscienceworld.org/gsa/geosphere/article/14/3/1343/530581/Teleseismic-Swave-tomography-of-South-Island-New},
	author = {Zietlow, Daniel W. and Sheehan, Anne F. and Bernardino, Melissa V.}
}
@article {Byrnes2017a,
	title = {Mantle dynamics beneath the discrete and diffuse plate boundaries of the Juan de Fuca plate: Results from Casascadia Initiative body wave tomography},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {18},
	number = {8},
	year = {2017},
	month = {aug},
	pages = {2906{\textendash}2929},
	issn = {1525-2027},
	doi = {10.1002/2017GC006980},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2017GC006980},
	author = {Byrnes, Joseph S. and Toomey, Douglas R. and Hooft, Emilie E. E. and N{\'a}b{\v e}lek, John and Braunmiller, Jochen}
}
@article {Lynner2017,
	title = {Mantle flow along the eastern North American margin inferred from shear wave splitting},
	journal = {Geology},
	volume = {45},
	number = {10},
	year = {2017},
	month = {oct},
	pages = {867{\textendash}870},
	issn = {0091-7613},
	doi = {10.1130/G38980.1},
	url = {http://pubs.geoscienceworld.org/geology/article/45/10/867/353518/Mantle-flow-along-the-eastern-North-American},
	author = {Lynner, Colton and Bodmer, Miles}
}
@mastersthesis {Byrnes2017,
	title = {Mantle flow and melting beneath young oceanic lithosphere: Seismic studies of the Gal{\'a}pagos Archipelago and the Juan de Fuca Plate},
	year = {2017},
	school = {University of Oregon},
	type = {phdPh.D.},
	url = {http://hdl.handle.net/1794/22638\%09},
	author = {Byrnes, Joseph}
}
@article {Flores2017,
	title = {Observations of Seismicity and Ground Motion in the Northeast U.S. Atlantic Margin from Ocean-Bottom Seismometer Data},
	journal = {Seismological Research Letters},
	volume = {88},
	number = {1},
	year = {2017},
	month = {jan},
	pages = {23{\textendash}31},
	issn = {0895-0695},
	doi = {10.1785/0220160079},
	url = {https://pubs.geoscienceworld.org/srl/article/88/1/23-31/314313},
	author = {Flores, Claudia H. and ten Brink, Uri S. and McGuire, Jeffrey J. and Collins, John A.}
}
@article {ball_remote_2017,
	title = {Remote detection of cryoacoustic signals using noise interferometry of seafloor pressure data},
	journal = {The Journal of the Acoustical Society of America},
	volume = {141},
	number = {5},
	year = {2017},
	note = {Publisher: Acoustical Society of America},
	month = {may},
	pages = {4047{\textendash}4047},
	issn = {0001-4966},
	doi = {10.1121/1.4989358},
	url = {https://asa.scitation.org/doi/10.1121/1.4989358},
	author = {Ball, Justin S. and Sheehan, Anne F. and Scambos, Ted}
}
@article {Shillington2016,
	title = {Acquisition of a Unique Onshore/Offshore Geophysical and Geochemical Dataset in the Northern Malawi (Nyasa) Rift},
	journal = {Seismological Research Letters},
	volume = {87},
	number = {6},
	year = {2016},
	month = {nov},
	pages = {1406{\textendash}1416},
	issn = {0895-0695},
	doi = {10.1785/0220160112},
	url = {https://pubs.geoscienceworld.org/srl/article/87/6/1406-1416/314187},
	author = {Shillington, Donna J. and Gaherty, James B. and Ebinger, Cynthia J. and Scholz, Christopher A. and Selway, Kate and Nyblade, Andrew A. and Bedrosian, Paul A. and Class, Cornelia and Nooner, Scott L. and Pritchard, Matthew E. and Elliott, Julie and Chindandali, Patrick R. N. and Mbogoni, Gaby and Ferdinand, Richard Wambura and Boniface, Nelson and Manya, Shukrani and Kamihanda, Godson and Saria, Elifuraha and Mulibo, Gabriel and Salima, Jalf and Mruma, Abdul and Kalindekafe, Leonard and Accardo, Natalie J. and Ntambila, Daud and Kachingwe, Marsella and Mesko, Gary T. and McCartney, Tannis and Maquay, Melania and O{\textquoteright}Donnell, J. P. and Tepp, Gabrielle and Mtelela, Khalfan and Trinhammer, Per and Wood, Douglas and Aaron, Ernest and Gibaud, Mark and Rapa, Martin and Pfeifer, Cathy and Mphepo, Felix and Gondwe, Duncan and Arroyo, Gabriella and Eddy, Celia and Kamoga, Brian and Moshi, Mary}
}
@article {Johnson2016,
	title = {Delayed dynamic triggering: Local seismicity leading up to three remote M >= 6 aftershocks of the 11 April 2012 M8.6 Indian Ocean earthquake},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {121},
	number = {1},
	year = {2016},
	month = {jan},
	pages = {134{\textendash}151},
	issn = {21699313},
	doi = {10.1002/2015JB012243},
	url = {http://doi.wiley.com/10.1002/2015JB012243},
	author = {Johnson, Christopher W. and B{\"u}rgmann, Roland}
}
@article {Ball2016,
	title = {Lithospheric shear velocity structure of South Island, New Zealand, from amphibious Rayleigh wave tomography},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {121},
	number = {5},
	year = {2016},
	month = {may},
	pages = {3686{\textendash}3702},
	issn = {21699313},
	doi = {10.1002/2015JB012726},
	url = {http://doi.wiley.com/10.1002/2015JB012726},
	author = {Ball, Justin S. and Sheehan, Anne F. and Stachnik, Joshua C. and Lin, Fan-Chi and Yeck, William L. and Collins, John A.}
}
@article {Chen2016,
	title = {Microseism source direction from noise cross-correlation},
	journal = {Geophysical Journal International},
	volume = {205},
	number = {2},
	year = {2016},
	month = {05/2016},
	pages = {810{\textendash}818},
	abstract = {Inhomogeneous noise sources surrounding stations produce asymmetric amplitudes in cross-correlation functions that yield preferential source directions. Here we show that preprocessing biases the dominant source direction estimate towards the source producing long-duration signals by down-weighting high-amplitude signals. Tests with both synthetic data and observations show that conventional preprocessing, where only earthquakes and local transients (e.g. trawling, fish impacts) are removed, is more sensitive to coherent energy, while one-bit preprocessing and running-absolute-mean preprocessing are more influenced by signal duration. Comparisons between different preprocessing methods are made on data from the Cascadia Initiative ocean bottom seismometer array, where we find that the total energy arriving from pelagic and coastal areas is similar. Moreover, pelagic-generated signals tend to be weaker but have longer duration, in contrast to coastal-generated signals that tend to be stronger but have shorter duration.},
	issn = {0956-540X},
	doi = {10.1093/gji/ggw055},
	url = {https://academic.oup.com/gji/article-lookup/doi/10.1093/gji/ggw055},
	author = {Chen, Zhao and Gerstoft, Peter and Bromirski, Peter D.}
}
@article {Berger2016,
	title = {An ocean bottom seismic observatory with near real-time telemetry},
	journal = {Earth and Space Science},
	volume = {3},
	number = {2},
	year = {2016},
	month = {feb},
	pages = {68{\textendash}77},
	issn = {2333-5084},
	doi = {10.1002/2015EA000137},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2015EA000137},
	author = {Berger, J. and Laske, G. and Babcock, J. and Orcutt, J.}
}
@article {Bowden2016,
	title = {Offshore Southern California lithospheric velocity structure from noise cross-correlation functions},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {121},
	number = {5},
	year = {2016},
	month = {may},
	pages = {3415{\textendash}3427},
	issn = {21699313},
	doi = {10.1002/2016JB012919},
	url = {http://doi.wiley.com/10.1002/2016JB012919},
	author = {Bowden, D. C. and Kohler, M. D. and Tsai, V. C. and Weeraratne, D. S.}
}
@article {Brodie2015,
	title = {Low frequency baleen whale calls detected on ocean-bottom seismometers in the Lau basin, southwest Pacific Ocean},
	journal = {The Journal of the Acoustical Society of America},
	volume = {137},
	number = {1},
	year = {2015},
	month = {jan},
	pages = {53{\textendash}62},
	issn = {0001-4966},
	doi = {10.1121/1.4904556},
	url = {http://asa.scitation.org/doi/10.1121/1.4904556},
	author = {Brodie, Dana C. and Dunn, Robert A.}
}
@article {Martin-Short2015,
	title = {Mantle flow geometry from ridge to trench beneath the Gorda{\textendash}Juan de Fuca plate system},
	journal = {Nature Geoscience},
	volume = {8},
	number = {12},
	year = {2015},
	month = {dec},
	pages = {965{\textendash}968},
	issn = {1752-0894},
	doi = {10.1038/ngeo2569},
	url = {http://www.nature.com/articles/ngeo2569},
	author = {Martin-Short, Robert and Allen, Richard M. and Bastow, Ian D. and Totten, Eoghan and Richards, Mark A.}
}
@article {Becel2015,
	title = {Origin of dipping structures in fast-spreading oceanic lower crust offshore Alaska imaged by multichannel seismic data},
	journal = {Earth and Planetary Science Letters},
	volume = {424},
	year = {2015},
	month = {aug},
	pages = {26{\textendash}37},
	issn = {0012821X},
	doi = {10.1016/j.epsl.2015.05.016},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0012821X15003052},
	author = {B{\'e}cel, Anne and Shillington, Donna J. and Nedimovi{\'c}, Mladen R. and Webb, Spahr C. and Kuehn, Harold}
}
@article {Barklage2015,
	title = {P and S velocity tomography of the Mariana subduction system from a combined land-sea seismic deployment},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {16},
	number = {3},
	year = {2015},
	month = {mar},
	pages = {681{\textendash}704},
	issn = {15252027},
	doi = {10.1002/2014GC005627},
	url = {http://doi.wiley.com/10.1002/2014GC005627},
	author = {Barklage, Mitchell and Wiens, Douglas A. and Conder, James A. and Pozgay, Sara and Shiobara, Hajime and Sugioka, Hiroko}
}
@article {Morton2015,
	title = {Preliminary Event Detection of Earthquakes Using the Cascadia Initiative Data},
	journal = {Seismological Research Letters},
	volume = {86},
	number = {5},
	year = {2015},
	month = {sep},
	pages = {1270{\textendash}1277},
	issn = {0895-0695},
	doi = {10.1785/0220150098},
	url = {https://pubs.geoscienceworld.org/srl/article/86/5/1270-1277/315541},
	author = {Morton, Emily A. and Bilek, Susan L.}
}
@article {Bell2015a,
	title = {Removing Noise from the Vertical Component Records of Ocean-Bottom Seismometers: Results from Year One of the Cascadia Initiative},
	journal = {Bulletin of the Seismological Society of America},
	volume = {105},
	number = {1},
	year = {2015},
	month = {feb},
	pages = {300{\textendash}313},
	issn = {0037-1106},
	doi = {10.1785/0120140054},
	url = {https://pubs.geoscienceworld.org/bssa/article/105/1/300-313/323517},
	author = {Bell, Samuel W. and Forsyth, Donald W. and Ruan, Youyi}
}
@article {Bodmer2015,
	title = {Seismic anisotropy beneath the Juan de Fuca plate system: Evidence for heterogeneous mantle flow},
	journal = {Geology},
	year = {2015},
	month = {nov},
	pages = {G37181.1},
	issn = {0091-7613},
	doi = {10.1130/G37181.1},
	url = {https://pubs.geoscienceworld.org/geology/article/43/12/1095-1098/131775},
	author = {Bodmer, Miles and Toomey, Douglas R. and Hooft, Emilie E. and N{\'a}b{\v e}lek, John and Braunmiller, Jochen}
}
@article {Menke2015,
	title = {Seismic anisotropy indicates ridge-parallel asthenospheric flow beneath the Eastern Lau Spreading Center},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {120},
	number = {2},
	year = {2015},
	month = {feb},
	pages = {976{\textendash}992},
	issn = {2169-9313},
	doi = {10.1002/2014JB011154},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2014JB011154},
	author = {Menke, William and Zha, Yang and Webb, Spahr C. and Blackman, Donna K.}
}
@inbook {Cheng2015,
	title = {Seismic Constraints on a Double-Layered Asymmetric Whole-Mantle Plume Beneath Hawai{\textquoteleft}i},
	year = {2015},
	month = {feb},
	pages = {19{\textendash}34},
	doi = {10.1002/9781118872079.ch2},
	url = {http://doi.wiley.com/10.1002/9781118872079.ch2},
	author = {Cheng, Cheng and Allen, Richard M. and Porritt, Rob W. and Ballmer, Maxim D.}
}
@article {Wei2015,
	title = {Seismic evidence of effects of water on melt transport in the Lau back-arc mantle},
	journal = {Nature},
	volume = {518},
	number = {7539},
	year = {2015},
	month = {feb},
	pages = {395{\textendash}398},
	issn = {0028-0836},
	doi = {10.1038/nature14113},
	url = {http://www.nature.com/articles/nature14113},
	author = {Wei, S. Shawn and Wiens, Douglas A. and Zha, Yang and Plank, Terry and Webb, Spahr C. and Blackman, Donna K. and Dunn, Robert A. and Conder, James A.}
}
@article {Trehu2015,
	title = {Seismicity of the Central Cascadia Continental Margin near 44.5 N: A Decadal View},
	journal = {Seismological Research Letters},
	volume = {86},
	number = {3},
	year = {2015},
	month = {may},
	pages = {819{\textendash}829},
	issn = {0895-0695},
	doi = {10.1785/0220140207},
	url = {https://pubs.geoscienceworld.org/srl/article/86/3/819-829/315628},
	author = {Trehu, A. M. and Braunmiller, J. and Davis, E.}
}
@article {Bell2015,
	title = {Shear Velocity Structure of Abyssal Plain Sediments in Cascadia},
	journal = {Seismological Research Letters},
	volume = {86},
	number = {5},
	year = {2015},
	month = {sep},
	pages = {1247{\textendash}1252},
	issn = {0895-0695},
	doi = {10.1785/0220150101},
	url = {https://pubs.geoscienceworld.org/srl/article/86/5/1247-1252/315523},
	author = {Bell, Samuel W. and Ruan, Youyi and Forsyth, Donald W.}
}
@article {toomey_cascadia_2014,
	title = {THE CASCADIA INITIATIVE: A Sea Change In Seismological Studies of Subduction Zones},
	journal = {Oceanography},
	volume = {27},
	number = {2},
	year = {2014},
	note = {Publisher: Oceanography Society},
	pages = {138{\textendash}150},
	abstract = {ABSTRACTIncreasing public awareness that the Cascadia subduction zone in the Pacific Northwest is capable of great earthquakes (magnitude 9 and greater) motivates the Cascadia Initiative, an ambitious onshore/offshore seismic and geodetic experiment that takes advantage of an amphibious array to study questions ranging from megathrust earthquakes, to volcanic arc structure, to the formation, deformation and hydration of the Juan De Fuca and Gorda Plates. Here, we provide an overview of the Cascadia Initiative, including its primary science objectives, its experimental design and implementation, and a preview of how the resulting data are being used by a diverse and growing scientific community. The Cascadia Initiative also exemplifies how new technology and community-based experiments are opening up frontiers for marine science. The new technology{\textemdash}shielded ocean bottom seismometers{\textemdash}is allowing more routine investigation of the source zone of megathrust earthquakes, which almost exclusively lies offshore and in shallow water. The Cascadia Initiative offers opportunities and accompanying challenges to a rapidly expanding community of those who use ocean bottom seismic data.},
	issn = {1042-8275},
	doi = {10.5670/oceanog.2014.49},
	url = {https://www.jstor.org/stable/24862164},
	author = {Toomey, Douglas R. and Allen, Richard M. and Barclay, Andrew H. and Bell, Samuel W. and Bromirski, Peter D. and Carlson, Richard L. and Chen, Xiaowei and Collins, John A. and Dziak, Robert P. and Evers, Brent and Forsyth, Donald W. and Gerstoft, Peter and Hooft, Emilie E.E. and Livelybrooks, Dean and Lodewyk, Jessica A. and Luther, Douglas S. and McGuire, Jeffrey J. and Schwartz, Susan Y. and Tolstoy, Maya and Tr{\'e}hu, Anne M. and Weirathmueller, Michelle and Wilcock, William S.D.}
}
@article {ball_joint_2014,
	title = {A joint Monte Carlo analysis of seafloor compliance, Rayleigh wave dispersion and receiver functions at ocean bottom seismic stations offshore New Zealand},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {15},
	number = {12},
	year = {2014},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/2014GC005412},
	pages = {5051{\textendash}5068},
	abstract = {Teleseismic body-wave imaging techniques such as receiver function analysis can be notoriously difficult to employ on ocean-bottom seismic data due largely to multiple reverberations within the water and low-velocity sediments. In lieu of suppressing this coherently scattered noise in ocean-bottom receiver functions, these site effects can be modeled in conjunction with shear velocity information from seafloor compliance and surface wave dispersion measurements to discern crustal structure. A novel technique to estimate 1-D crustal shear-velocity profiles from these data using Monte Carlo sampling is presented here. We find that seafloor compliance inversions and P-S conversions observed in the receiver functions provide complimentary constraints on sediment velocity and thickness. Incoherent noise in receiver functions from the MOANA ocean bottom seismic experiment limit the accuracy of the practical analysis at crustal scales, but synthetic recovery tests and comparison with independent unconstrained nonlinear optimization results affirm the utility of this technique in principle.},
	keywords = {Monte Carlo, New Zealand, OBS receiver function, seafloor compliance, sediment shear modes, surface waves},
	issn = {1525-2027},
	doi = {10.1002/2014GC005412},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2014GC005412},
	author = {Ball, Justin S. and Sheehan, Anne F. and Stachnik, Joshua C. and Lin, Fan-Chi and Collins, John A.}
}
@article {ruan_marine_2014,
	title = {Marine sediment shear velocity structure from the ratio of displacement to pressure of Rayleigh waves at seafloor},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {119},
	number = {8},
	year = {2014},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/2014JB011162},
	pages = {6357{\textendash}6371},
	abstract = {AbstractThe complex ratio of vertical displacement to pressure (D/P) at seafloor is a function of frequency. It is sensitive to the subsurface elastic properties, particularly the shear modulus, and therefore can be used to determine the shear velocity and thickness of marine sediments. Instead of using compliance in response to loading of long-period infragravity waves as in previous studies, we investigate the transfer function from pressure to displacement using Rayleigh waves generated by microseisms and earthquakes. We find that at frequencies between 0.1 and 0.2 Hz, the Rayleigh wave transfer function is very sensitive to marine sediments and can be reliably obtained from microseism noise. Using a surface wave mode method, we calculate synthetic D/P ratios and examine their sensitivity to water depth, shear wave speed, and thickness of sediments. We develop a method to invert the Rayleigh wave D/P ratio for a regional 1-D profile of sediment shear wave speed and associated sediment thickness beneath each ocean bottom seismograph (OBS). We apply our method to a group of deep water OBSs deployed in the Cascadia Initiative and obtain a well-resolved depth-dependent shear wave speed for sediments on the Juan de Fuca plate and shear wave traveltime delays caused by sediments at each station.},
	keywords = {admittance, D/P ratio method, marine sediment, microseism noise, Rayleigh waves, shear wave speed},
	issn = {2169-9356},
	doi = {10.1002/2014JB011162},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2014JB011162},
	author = {Ruan, Youyi and Forsyth, Donald W. and Bell, Samuel W.}
}
@article {wolfson-schwehr_relationship_2014,
	title = {The relationship between seismicity and fault structure on the Discovery transform fault, East Pacific Rise},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {15},
	number = {9},
	year = {2014},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/2014GC005445},
	pages = {3698{\textendash}3712},
	abstract = {There is a global seismic moment deficit on mid-ocean ridge transform faults, and the largest earthquakes on these faults do not rupture the full fault area. We explore the influence of physical fault structure, including step-overs in the fault trace, on the seismic behavior of the Discovery transform fault, 4S on the East Pacific Rise. One year of microseismicity recorded during a 2008 ocean bottom seismograph deployment (24,377 0 ML 4.6 earthquakes) and 24 years of Mw 5.4 earthquakes obtained from the Global Centroid Moment Tensor catalog, are correlated with surface fault structure delineated from high-resolution multibeam bathymetry. Each of the 15 5.4 Mw 6.0 earthquakes that occurred on Discovery between 1 January 1990 and 1 April 2014 was relocated into one of five distinct rupture patches using a teleseismic surface wave cross-correlation technique. Microseismicity was relocated using the HypoDD relocation algorithm. The western fault segment of Discovery (DW) is composed of three zones of varying structure and seismic behavior: a zone with no large events and abundant microseismicity, a fully coupled zone with large earthquakes, and a complex zone with multiple fault strands and abundant seismicity. In general, microseismicity is reduced within the patches defined by the large, repeating earthquakes. While the extent of the large rupture patches on DW correlates with physical features in the bathymetry, step-overs in the primary fault trace are not observed at patch boundaries, suggesting along-strike heterogeneity in fault zone properties controls the size and location of the large events.},
	keywords = {earthquakes, East Pacific Rise, fault structure, transform fault},
	issn = {1525-2027},
	doi = {10.1002/2014GC005445},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2014GC005445},
	author = {Wolfson-Schwehr, Monica and Boettcher, Margaret S. and McGuire, Jeffrey J. and Collins, John A.}
}
@article {booth_upper_2014,
	title = {Upper mantle Q structure beneath old seafloor in the western Pacific},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {119},
	number = {4},
	year = {2014},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/2013JB010589},
	pages = {3448{\textendash}3461},
	abstract = {The Pacific Lithosphere Anisotropy and Thickness Experiment ocean bottom seismometer array south of the Shatsky Rise allows imaging the attenuation structure of the upper mantle in the oldest parts of the Pacific Ocean. The array consisted of eight seismometers with a lateral extent of 200 km by 600 km. Intermediate- and deep-focus earthquake sources in the Mariana and Izu-Bonin subduction zones provide paths that probe different depths beneath the seafloor. Acceleration spectra from the vertical component of P waves are inverted for the attenuation operator and corner frequency. Pn propagation indicates very high Qp values in the lithosphere, of order 1000, while path-average Qp values in the upper mantle are on the order of 400. The variety of source epicentral distances and depths enables us to deduce the vertical Qp-1 structure of the upper mantle. Using the amplitude spectra directly in a weighted least squares problem that accounts for the effects of triplications in the traveltime curves, we invert for Qp-1 as a function of depth. We demonstrate that Qp is frequency dependent and adopt a power law dependence with coefficient α = 0.27. We resolve three distinct layers using a reference frequency of 1 Hz with Qp on the order of 145 at depths 100{\textendash}250 km, Qp on the order of 350 at depths 250{\textendash}410 km, and very high Qp with attenuation indistinguishable from zero for depths below 410 km. The P waves have a component of scattering, and thus, Qp-1 represents the maximum intrinsic attenuation beneath normal undisturbed oceanic lithosphere.},
	keywords = {attenuation, Pacific, upper mantle},
	issn = {2169-9356},
	doi = {10.1002/2013JB010589},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2013JB010589},
	author = {Booth, Catherine M. and Forsyth, Donald W. and Weeraratne, Dayanthie S.}
}
@article {stephen_deep_2013,
	title = {Deep seafloor arrivals in long range ocean acoustic propagation},
	journal = {The Journal of the Acoustical Society of America},
	volume = {134},
	number = {4},
	year = {2013},
	note = {Publisher: Acoustical Society of America},
	month = {oct},
	pages = {3307{\textendash}3317},
	abstract = {Ocean bottom seismometer observations at 5000 m depth during the long-range ocean acoustic propagation experiment in the North Pacific in 2004 show robust, coherent, late arrivals that are not readily explained by ocean acoustic propagation models. These {\textquotedblleft}deep seafloor{\textquotedblright} arrivals are the largest amplitude arrivals on the vertical particle velocity channel for ranges from 500 to 3200 km. The travel times for six (of 16 observed) deep seafloor arrivals correspond to the sea surface reflection of an out-of-plane diffraction from a seamount that protrudes to about 4100 m depth and is about 18 km from the receivers. This out-of-plane bottom-diffracted surface-reflected energy is observed on the deep vertical line array about 35 dB below the peak amplitude arrivals and was previously misinterpreted as in-plane bottom-reflected surface-reflected energy. The structure of these arrivals from 500 to 3200 km range is remarkably robust. The bottom-diffracted surface-reflected mechanism provides a means for acoustic signals and noise from distant sources to appear with significant strength on the deep seafloor.},
	issn = {0001-4966},
	doi = {10.1121/1.4818845},
	url = {https://asa.scitation.org/doi/full/10.1121/1.4818845},
	author = {Stephen, Ralph A. and Thompson Bolmer, S. and Udovydchenkov, Ilya A. and Worcester, Peter F. and Dzieciuch, Matthew A. and Andrew, Rex K. and Mercer, James A. and Colosi, John A. and Howe, Bruce M.}
}
@article {worcester_north_2013,
	title = {The North Pacific Acoustic Laboratory deep-water acoustic propagation experiments in the Philippine Sea},
	journal = {The Journal of the Acoustical Society of America},
	volume = {134},
	number = {4},
	year = {2013},
	note = {Publisher: Acoustical Society of America},
	month = {oct},
	pages = {3359{\textendash}3375},
	abstract = {A series of experiments conducted in the Philippine Sea during 2009{\textendash}2011 investigated deep-water acoustic propagation and ambient noise in this oceanographically and geologically complex region: (i) the 2009 North Pacific Acoustic Laboratory (NPAL) Pilot Study/Engineering Test, (ii) the 2010{\textendash}2011 NPAL Philippine Sea Experiment, and (iii) the Ocean Bottom Seismometer Augmentation of the 2010{\textendash}2011 NPAL Philippine Sea Experiment. The experimental goals included (a) understanding the impacts of fronts, eddies, and internal tides on acoustic propagation, (b) determining whether acoustic methods, together with other measurements and ocean modeling, can yield estimates of the time-evolving ocean state useful for making improved acoustic predictions, (c) improving our understanding of the physics of scattering by internal waves and spice, (d) characterizing the depth dependence and temporal variability of ambient noise, and (e) understanding the relationship between the acoustic field in the water column and the seismic field in the seafloor. In these experiments, moored and ship-suspended low-frequency acoustic sources transmitted to a newly developed distributed vertical line array receiver capable of spanning the water column in the deep ocean. The acoustic transmissions and ambient noise were also recorded by a towed hydrophone array, by acoustic Seagliders, and by ocean bottom seismometers.},
	issn = {0001-4966},
	doi = {10.1121/1.4818887},
	url = {https://asa.scitation.org/doi/full/10.1121/1.4818887},
	author = {Worcester, Peter F. and Dzieciuch, Matthew A. and Mercer, James A. and Andrew, Rex K. and Dushaw, Brian D. and Baggeroer, Arthur B. and Heaney, Kevin D. and D{\textquoteright}Spain, Gerald L. and Colosi, John A. and Stephen, Ralph A. and Kemp, John N. and Howe, Bruce M. and Van Uffelen, Lora J. and Wage, Kathleen E.}
}
@article {wech_tectonic_2013,
	title = {Tectonic Tremor Recorded by Ocean Bottom Seismometers},
	journal = {Seismological Research Letters},
	volume = {84},
	number = {5},
	year = {2013},
	month = {sep},
	pages = {752{\textendash}758},
	issn = {0895-0695},
	doi = {10.1785/0220120184},
	url = {https://doi.org/10.1785/0220120184},
	author = {Wech, A. G. and Sheehan, A. F. and Boese, C. M. and Townend, J. and Stern, T. A. and Collins, J. A.}
}
@article {mcguire_variations_2012,
	title = {Variations in earthquake rupture properties along the Gofar transform fault, East Pacific Rise},
	journal = {Nature Geoscience},
	volume = {5},
	number = {5},
	year = {2012},
	note = {Number: 5 Publisher: Nature Publishing Group},
	month = {may},
	pages = {336{\textendash}341},
	abstract = {Mid-ocean ridge transform faults experience more foreshocks than continental faults, yet the mainshock rarely ruptures the entire fault. Analysis of seismic data from the Gofar transform fault at the East Pacific Rise indicates that the foreshock region has different material properties from the mainshock region, and acts as a barrier to rupture propagation.},
	keywords = {seismology},
	issn = {1752-0908},
	doi = {10.1038/ngeo1454},
	url = {https://www.nature.com/articles/ngeo1454},
	author = {McGuire, Jeffrey J. and Collins, John A. and Gou{\'e}dard, Pierre and Roland, Emily and Lizarralde, Dan and Boettcher, Margaret S. and Behn, Mark D. and van der Hilst, Robert D.}
}
@article {bostock_wavefield_2012,
	title = {Wave-Field Decomposition of Ocean Bottom Seismograms},
	journal = {Bulletin of the Seismological Society of America},
	volume = {102},
	number = {4},
	year = {2012},
	month = {aug},
	pages = {1681{\textendash}1692},
	abstract = {Seismograms recorded on the seafloor are affected by reverberations in the overlying ocean layer. We examine the feasibility of removing these reverberations through a 1D wave-field decomposition based on a reflection{\textendash}transmission formulation of the problem. Two decomposition schemes are presented. The first scheme involves a simple manipulation of the fundamental matrix relating stress and displacement of plane harmonic waves to upgoing and downgoing wavevector coefficients and requires measurement of both ocean bottom displacement and pressure. The second approach involves only displacement recordings and knowledge of the water column depth. This latter quantity will generally be known a priori from deployment logs, or, alternatively, it may be estimated using vertical displacement and pressure seismograms in a preprocessing step. Both approaches require prior information on seabed properties. In the case of P-wave incidence, the decomposition depends primarily on the seabed S velocity β0. This quantity can be determined by examining trial decompositions over a range of β0{\textquoteright}s and selecting the value that minimizes the energy of the upgoing S-wave component at the arrival time of the incident wave. We apply this approach to synthetic seismograms for a simple Earth structure and to recordings of two large events from the Central Oregon Locked Zone Array (COLZA) on the continental margin of Oregon. The real data indicate that the wave-field decompositions are largely successful at lower frequencies (\&lt;0.1  Hz) but that 3D scattering, likely originating near the sediment{\textendash}basement contact, is manifested at higher frequencies.},
	issn = {0037-1106},
	doi = {10.1785/0120110162},
	url = {https://doi.org/10.1785/0120110162},
	author = {Bostock, M. G. and Trehu, A. M.}
}
@article {laske_asymmetric_2011,
	title = {Asymmetric shallow mantle structure beneath the Hawaiian Swell-evidence from Rayleigh waves recorded by the PLUME network},
	journal = {Geophysical Journal International},
	volume = {187},
	number = {3},
	year = {2011},
	pages = {1725{\textendash}1742},
	abstract = {We present models of the 3-D shear velocity structure of the lithosphere and asthenosphere beneath the Hawaiian hotspot and surrounding region. The models are derived from long-period Rayleigh-wave phase velocities that were obtained from the analysis of seismic recordings collected during two year-long deployments for the Hawaiian Plume-Lithosphere Undersea Mantle Experiment. For this experiment, broad-band seismic sensors were deployed at nearly 70 seafloor sites as well as 10 sites on the Hawaiian Islands. Our seismic images result from a two-step inversion of path-averaged dispersion curves using the two-station method. The images reveal an asymmetry in shear velocity structure with respect to the island chain, most notably in the lower lithosphere at depths of 60 km and greater, and in the asthenosphere. An elongated, 100-km-wide and 300-km-long low-velocity anomaly reaches to depths of at least 140 km. At depths of 60 km and shallower, the lowest velocities are found near the northern end of the island of Hawaii. No major velocity anomalies are found to the south or southeast of Hawaii, at any depth. The low-velocity anomaly in the asthenosphere is consistent with an excess temperature of 200-250 {\textdegree}C and partial melt at the level of a few percent by volume, if we assume that compositional variations as a result of melt extraction play a minor role. We also image small-scale low-velocity anomalies within the lithosphere that may be associated with the volcanic fields surrounding the Hawaiian Islands.},
	issn = {0956-540X},
	doi = {10.1111/j.1365-246X.2011.05238.x},
	url = {https://doi.org/10.1111/j.1365-246X.2011.05238.x},
	author = {Laske, Gabi and Markee, Amanda and Orcutt, John A. and Wolfe, Cecily J. and Collins, John A. and Solomon, Sean C. and Detrick, Robert S. and Bercovici, David and Hauri, Erik H.}
}
@article {wolfe_mantle_2011,
	title = {Mantle P-wave velocity structure beneath the Hawaiian hotspot},
	journal = {Earth and Planetary Science Letters},
	volume = {303},
	number = {3},
	year = {2011},
	month = {mar},
	pages = {267{\textendash}280},
	abstract = {Three-dimensional images of P-wave velocity structure beneath the Hawaiian Islands, obtained from a network of seafloor and land seismometers, show an upper-mantle low-velocity anomaly that is elongated in the direction of the island chain and surrounded by a high-velocity anomaly in the shallow upper mantle that is parabolic in map view. Low velocities continue downward to the mantle transition zone between 410 and 660km depth and extend into the topmost lower mantle, although the resolution of lower mantle structure from this data set is limited. Comparisons of inversions with separate data sets at different frequencies suggest that contamination by water reverberations is not markedly biasing the P-wave imaging of mantle structure. Many aspects of the P-wave images are consistent with independent tomographic images of S-wave velocity in the region, but there are some differences in upper mantle structure between P-wave and S-wave velocities. Inversions without station terms show a southwestward shift in the location of lowest P-wave velocities in the uppermost mantle relative to the pattern for shear waves, and inversions with station terms show differences between P-wave and S-wave velocity heterogeneity in the shallow upper mantle beneath and immediately east of the island of Hawaii. Nonetheless, the combined data sets are in general agreement with the hypothesis that the Hawaiian hotspot is the result of an upwelling, high-temperature plume. The broad upper-mantle low-velocity region beneath the Hawaiian Islands may reflect the diverging {\textquotedblleft}pancake{\textquotedblright} at the top of the upwelling zone; the surrounding region of high velocities could represent a downwelling curtain; and the low-velocity anomalies southeast of Hawaii in the transition zone and topmost lower mantle are consistent with predictions of plume tilt.},
	keywords = {finite-frequency tomography, Hawaii, hotspot, mantle plume},
	issn = {0012-821X},
	doi = {10.1016/j.epsl.2011.01.004},
	url = {https://www.sciencedirect.com/science/article/pii/S0012821X11000161},
	author = {Wolfe, Cecily J. and Solomon, Sean C. and Laske, Gabi and Collins, John A. and Detrick, Robert S. and Orcutt, John A. and Bercovici, David and Hauri, Erik H.}
}
@article {williams_seismicity_2011,
	title = {Seismicity at the Cascadia Plate Boundary beneath the Oregon Continental Shelf},
	journal = {Bulletin of the Seismological Society of America},
	volume = {101},
	number = {3},
	year = {2011},
	pages = {940{\textendash}950},
	abstract = {Since 2003, 39 small earthquakes have been detected off the coast of central Oregon in the nominally locked part of the Cascadia subduction zone, where very little seismic activity has been recorded in spite of a paleoseismic record of great subduction events. Although the regional earthquake bulletin reports depths of 29 and 28~km for the two largest events (Mw~4.9 and Mw~4.7, which occurred in 2004), analysis by Tr{\'e}hu et~al. (2008) indicates that they were low-angle thrust events that occurred on the plate boundary at depths of 9{\textendash}11 and 16~km, respectively. Because of sparse onshore station coverage, most of the smaller events have large location uncertainties. Double-difference relative location of 30 of these earthquakes reveals two tight clusters approximately 30~km apart; each cluster is associated with one of the two larger events. Within each cluster, relocation reduces the hypocenter depth spread from \&gt;15 km to \&lt;3 km, with uncertainties on the order of 0.1~km. The relocations, combined with independent absolute hypocenter locations for two 2008 events using a deployment of land and ocean-bottom seismometers, suggest that the seismicity occurred at plate boundary depths, possibly on the Cascadia megathrust. This concentrated activity in the seismogenic zone may represent patches on the fault plane with anomalous frictional characteristics, possibly caused by subducted topographic features, which can affect the propagation of a large megathrust rupture.},
	issn = {0037-1106},
	doi = {10.1785/0120100198},
	url = {https://doi.org/10.1785/0120100198},
	author = {Williams, Mark C. and Tr{\'e}hu, Anne M. and Braunmiller, Jochen}
}
@article {bezada_subduction_2010,
	title = {Subduction in the southern Caribbean: Images from finite-frequency P wave tomography},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {115},
	number = {B12},
	year = {2010},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2010JB007682},
	abstract = {The eastern boundary of the Caribbean plate is marked by subduction of the Atlantic under the Lesser Antilles. The southeastern plate boundary is characterized by a strike-slip margin, while different configurations of subduction of the southwest Caribbean under South America have been proposed. We investigate the slab geometry in the upper mantle using multiple-frequency, teleseismic P wave tomography. Waveforms from P and PKPdf phases from 285 (Mb > 5.0) events occurring at epicentral distances from 30{\textdegree} to 90{\textdegree} and greater than 150{\textdegree} were bandpass filtered and cross-correlated to obtain up to three sets of delay times for each event. The delay times were inverted using approximate first Fresnel zone sensitivity kernels. Our results show the subducting Atlantic slab, as well as a second slab in the west of the study area that we interpret as a subducting fragment of the Caribbean plate. Both slabs have steep dips where imaged and can be traced to depths greater than 600 km. These results are consistent with transition zone boundary topography as determined by receiver function analysis. The Atlantic slab extends continent-ward south of the plate bounding strike-slip margin. We interpret this extension as continental margin lithospheric mantle that is detaching from beneath South America and subducting along with the oceanic Atlantic slab. The steep subduction of the Caribbean occurs \~{}500 km landward from the trench, implying an initial stage of shallow subduction as far to the east as the Lake Maracaibo-M{\'e}rida Andes region, as has been inferred from intermediate depth seismicity.},
	keywords = {P-wave tomography, southern Caribbean, subduction},
	issn = {2156-2202},
	doi = {10.1029/2010JB007682},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2010JB007682},
	author = {Bezada, M. J. and Levander, A. and Schmandt, B.}
}
@article {stephen_deep_2009,
	title = {Deep seafloor arrivals: An unexplained set of arrivals in long-range ocean acoustic propagation},
	journal = {The Journal of the Acoustical Society of America},
	volume = {126},
	number = {2},
	year = {2009},
	note = {Publisher: Acoustical Society of America},
	month = {aug},
	pages = {599{\textendash}606},
	abstract = {Receptions, from a ship-suspended source (in the band 50{\textendash}100Hz 50 {\textendash} 100 Hz ) to an ocean bottom seismometer (about 5000m 5000 m depth) and the deepest element on a vertical hydrophone array (about 750m 750 m above the seafloor) that were acquired on the 2004 Long-Range Ocean Acoustic Propagation Experiment in the North Pacific Ocean, are described. The ranges varied from 50to3200km 50 to 3200 km . In addition to predicted ocean acoustic arrivals and deep shadow zone arrivals (leaking below turning points), {\textquotedblleft}deep seafloor arrivals,{\textquotedblright} that are dominant on the seafloor geophone but are absent or very weak on the hydrophone array, are observed. These deep seafloor arrivals are an unexplained set of arrivals in ocean acoustics possibly associated with seafloor interface waves.},
	issn = {0001-4966},
	doi = {10.1121/1.3158826},
	url = {https://asa.scitation.org/doi/full/10.1121/1.3158826},
	author = {Stephen, Ralph A. and Bolmer, S. Thompson and Dzieciuch, Matthew A. and Worcester, Peter F. and Andrew, Rex K. and Buck, Linda J. and Mercer, James A. and Colosi, John A. and Howe, Bruce M.}
}
@article {wolfe_mantle_2009,
	title = {Mantle Shear-Wave Velocity Structure Beneath the Hawaiian Hot Spot},
	journal = {Science},
	volume = {326},
	number = {5958},
	year = {2009},
	note = {Publisher: American Association for the Advancement of Science},
	month = {dec},
	pages = {1388{\textendash}1390},
	abstract = {Defining the mantle structure that lies beneath hot spots is important for revealing their depth of origin. Three-dimensional images of shear-wave velocity beneath the Hawaiian Islands, obtained from a network of sea-floor and land seismometers, show an upper-mantle low-velocity anomaly that is elongated in the direction of the island chain and surrounded by a parabola-shaped high-velocity anomaly. Low velocities continue downward to the mantle transition zone between 410 and 660 kilometers depth, a result that is in agreement with prior observations of transition-zone thinning. The inclusion of SKS observations extends the resolution downward to a depth of 1500 kilometers and reveals a several-hundred-kilometer-wide region of low velocities beneath and southeast of Hawaii. These images suggest that the Hawaiian hot spot is the result of an upwelling high-temperature plume from the lower mantle.},
	doi = {10.1126/science.1180165},
	url = {https://www.science.org/doi/full/10.1126/science.1180165},
	author = {Wolfe, Cecily J. and Solomon, Sean C. and Laske, Gabi and Collins, John A. and Detrick, Robert S. and Orcutt, John A. and Bercovici, David and Hauri, Erik H.}
}
@article {clark_identification_2008,
	title = {Identification and tectonic implications of a tear in the South American plate at the southern end of the Lesser Antilles},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {9},
	number = {11},
	year = {2008},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2008GC002084},
	abstract = {In the southeast corner of the Caribbean, westward subduction of (Atlantic) oceanic South America beneath the Lesser Antilles transitions to east-west transform motion between continental South America and the Caribbean plate. This geometry requires negatively buoyant, subducting, oceanic South American lithosphere to progressively detach from positively buoyant, continental South American lithosphere. The most widely accepted model is slab break-off, with oblique arc-continent collision and northwest dipping, continental subduction precipitating narrow rifting in the subducting slab. In contrast, the subduction-transform edge propagator (STEP) model conceptualizes progressive detachment along a vertical, dip-slip tear through the lithosphere, with stress focused at the edge of the propagating transform boundary. We present four types of seismic data to resolve the ongoing lithospheric detachment: local seismicity, receiver functions, wide-angle seismic velocity inversion, and a regional, balanced cross section constrained by petroleum industry data. These four data sets image a near-vertical tear extending through the entire lithosphere, revealing a key mechanism for the structural evolution of Venezuela.},
	keywords = {jelly sandwich, lithospheric detachment, mantle dynamics, slab break-off, STEP, tear},
	issn = {1525-2027},
	doi = {10.1029/2008GC002084},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2008GC002084},
	author = {Clark, S. A. and Sobiesiak, M. and Zelt, C. A. and Magnani, M. B. and Miller, M. S. and Bezada, M. J. and Levander, A.}
}
@article {niu_receiver_2007,
	title = {Receiver function study of the crustal structure of the southeastern Caribbean plate boundary and Venezuela},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {112},
	number = {B11},
	year = {2007},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2006JB004802},
	abstract = {We have investigated crustal thickness and composition across the southeastern Caribbean plate boundary with the receiver function technique. We used teleseismic data recorded by a temporary broadband array deployed under the BOLIVAR project and the permanent national seismic network of Venezuela. We used the primary P-to-S conversion and crustal reverberations to estimate crustal thickness and average crustal VP/VS ratio over the region. We observe large variations in crustal thickness and Poisson{\textquoteright}s ratio. Estimated Moho depth ranges from \~{}16 km beneath the southeastern Caribbean Sea to \~{}52 km beneath northeastern Venezuela and the Venezuelan Andes. There is a good correlation between crustal structure and tectonic terranes. Data from the Precambrian Guayana Shield suggest that the underlying crustal structure is relatively uniform with a moderate thickness (\~{}37 km) and an intermediate composition. A thick crust is found below the foreland basins. The two mountain systems in northern Venezuela, the Serrania del Interior and the Serrania del Falcon, have a thin crust with arc composition and are likely dynamically supported by elastic rebound or underthrusting of the oceanic plateau that characterizes the southern Caribbean. On the other hand, the Venezuelan Andes and Perija Range on the western side of the country are probably isostatically balanced by thick crustal roots.},
	keywords = {Moho depth, southeast Caribbean, VP/VS ratio},
	issn = {2156-2202},
	doi = {10.1029/2006JB004802},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2006JB004802},
	author = {Niu, Fenglin and Bravo, Tammy and Pavlis, Gary and Vernon, Frank and Rendon, Herbert and Bezada, Maximiliano and Levander, Alan}
}
@article {lizarralde_variation_2007,
	title = {Variation in styles of rifting in the Gulf of California},
	journal = {Nature},
	volume = {448},
	number = {7152},
	year = {2007},
	note = {Number: 7152 Publisher: Nature Publishing Group},
	month = {jul},
	pages = {466{\textendash}469},
	abstract = {Results from the PESCADOR seismic experiment in the Gulf of California provide new insight into rifting {\textemdash} the process that ruptures continents and forms new ocean basins. Unpredicted variations in magmatic activity in continental rifts are commonly attributed to variations in mantle temperature, but such thermal variations tend to occur over large length scales. The new results reveal large differences in rifting style and magmatism over short lateral distances. This suggests that the observed range in magmatism is caused not by variation in temperature, but rather by variability in mantle composition and fertility {\textemdash} the intrinsic capacity of the underlying mantle to produce melt.},
	keywords = {Humanities and Social Sciences, multidisciplinary, Science},
	issn = {1476-4687},
	doi = {10.1038/nature06035},
	url = {https://www.nature.com/articles/nature06035},
	author = {Lizarralde, Daniel and Axen, Gary J. and Brown, Hillary E. and Fletcher, John M. and Gonz{\'a}lez-Fern{\'a}ndez, Antonio and Harding, Alistair J. and Holbrook, W. Steven and Kent, Graham M. and Paramo, Pedro and Sutherland, Fiona and Umhoefer, Paul J.}
}
