@article {liu_-situ_2023,
	title = {In-Situ Vp/Vs Reveals Fault-Zone Material Variation at the Westernmost Gofar Transform Fault, East Pacific Rise},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {128},
	number = {3},
	year = {2023},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2022JB025310},
	month = {03/2023},
	pages = {e2022JB025310},
	abstract = {Ocean transform faults often generate characteristic earthquakes that repeatedly rupture the same fault patches. The westernmost Gofar transform fault quasi-periodically hosts \~{}M6 earthquakes every \~{}5 years, and microseismicity suggests that the fault is segmented into five distinct zones, including a rupture barrier zone that may have modulated the rupture of adjacent M6 earthquakes. However, the relationship between the systematic slip behavior of the Gofar fault and the fault material properties is still poorly known. Specifically, the role of pore fluids in regulating the slip of the Gofar fault is unclear. Here, we use differential travel times between nearby earthquakes to estimate the in-situ Vp/Vs of the fault-zone materials. We apply this technique to the dataset collected by an ocean-bottom-seismometer network deployed around the Gofar fault in 2008, which recorded abundant microearthquakes, and find a moderate Vp/Vs of 1.75{\textendash}1.80 in the rupture barrier zone and a low Vp/Vs of 1.61{\textendash}1.69 in the down-dip edge of the 2008 M6 rupture zone. This lateral variation in Vp/Vs may be caused by both pore fluids and chemical alteration. We also find a 5\%{\textendash}10\% increase in Vp/Vs in the barrier zone during the 9 months before the mainshock. This increase may have been caused by fluid migrations or slip transients in the barrier zone.},
	keywords = {fault-zone structure, ocean-bottom seismometer, oceanic transform fault, pore fluids, slip dilatancy, VP/VS ratio},
	issn = {2169-9356},
	doi = {10.1029/2022JB025310},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2022JB025310},
	author = {Liu, Tianze and Gong, Jianhua and Fan, Wenyuan and Lin, Guoqing}
}
@article {wei_improved_2022,
	title = {An Improved Earthquake Catalog During the 2018 K{\i}̄lauea Eruption From Combined Onshore and Offshore Seismic Arrays},
	journal = {Earth and Space Science},
	volume = {9},
	number = {6},
	year = {2022},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2021EA001979},
	month = {06/2022},
	pages = {e2021EA001979},
	abstract = {The Island of Hawai{\textquoteright}i was formed by repeated eruptions of basalts at an oceanic hotspot. K{\i}̄lauea, the youngest among the subaerial volcanoes of the island, erupted intensely in 2018. The eruption provided an opportunity to look into the mechanisms that operate at the volcano and associated earthquake activities, as it was recorded simultaneously, for the first time, by onshore and offshore seismometers. We used most of the publicly available seismic data during the eruption period, including temporary arrays, to build a more complete earthquake catalog during the eruption than that provided by the Hawaiian Volcano Observatory. We used a short-time-average/long-time-average method to identify potential earthquakes. The detections were associated with events and automatically picked with P-wave and S-wave arrivals, which were used to locate the events in a three-dimensional velocity model. After re-examining these earthquake events, their coda/duration magnitudes were determined. The resulting half-year catalog contains 375,736 events with one of the highest daily earthquake numbers ever reported (6,128 on 21 June 2018). A great number of events were recorded during the caldera collapses, from its beginning until its rapid ending. The catalog also contains abundant events near the Pu{\textquoteright}u{\textquoteleft}o{\textquoteleft}o vent and in the lower East Rift Zone, where an increase of seismicity in mid-July and August indicated a step-up in magma intrusion after the eruption.},
	keywords = {eruption, K{\i}̄lauea, offshore, onshore, seismicity},
	issn = {2333-5084},
	doi = {10.1029/2021EA001979},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2021EA001979},
	author = {Wei, XiaoZhuo and Shen, Yang and Caplan-Auerbach, Jacqueline and Morgan, Julia K.}
}
@article {carchedi_investigating_2022,
	title = {Investigating Short-Period Lake-Generated Microseisms Using a Broadband Array of Onshore and Lake-Bottom Seismometers},
	journal = {Seismological Research Letters},
	volume = {93},
	number = {3},
	year = {2022},
	month = {02/2022},
	pages = {1585{\textendash}1600},
	abstract = {Recent analyses of ambient seismic noise proximal to large lakes identify excitations between periods of 0.5 and 5~s as lake-generated microseisms, though the mechanisms producing them remain unclear in the absence of distinct spectral peaks. We present a unique data set combining onshore and offshore seismometers to investigate the dominant parameters controlling water-to-solid-earth seismic coupling in a lacustrine environment. Using a set of broadband observations that include six lake-bottom seismometers, we compare signals collected both within and around Lake Malawi (Nyasa) in southeastern Africa, the fifth largest freshwater lake in the world. We document clear evidence for two peaks within the lake microseism band, with pervasive diurnal excitations between periods of \~{}0.6{\textendash}1.3 and \~{}1.3{\textendash}3~s. Variations in spectral behavior as a function of recording depth and proximity to both steep lake-floor slopes and the shoreline suggest that the spectral bands may correspond to single- and double-frequency generation processes, akin to primary and secondary ocean microseisms generated by the shoaling of wind-driven gravity waves along shorelines and wave interactions within the open body of water, respectively. However, both the absolute amplitudes and temporal evolution we observe in these two bands are complex and often inconsistent with traditional microseism theory. Therefore, these spectral bands may alternatively result from complex wave{\textendash}wave interaction at the lake surface within the enclosed northern end of the lake. The diurnal behavior of lake microseisms, as well as their polarizations, suggest that the wave energy is driven by a combination of seasonally varying nighttime winds funneled by lakeshore topography and waveguide effects. This work also provides a glimpse into seasonal variation in lacustrine ambient seismic noise and thus also into lake processes.},
	issn = {0895-0695},
	doi = {10.1785/0220210155},
	url = {https://doi.org/10.1785/0220210155},
	author = {Carchedi, Christopher James William and Gaherty, James B. and Webb, Spahr C. and Shillington, Donna J.}
}
@article {dobashi_improving_2021,
	title = {Improving Detectability of Seafloor Deformation From Bottom Pressure Observations Using Numerical Ocean Models},
	journal = {Frontiers in Earth Science},
	volume = {8},
	year = {2021},
	month = {01/2021},
	abstract = {We investigated ocean bottom pressure (OBP) observation data at six plate subduction zones around the Pacific Ocean. The six regions included the Hikurangi Trough, the Nankai Trough, the Japan Trench, the Aleutian Trench, the Cascadia Subduction Zone, and the Chile Trench. For the sake of improving the detectability of seafloor deformation using OBP observations, we used numerical ocean models to represent realistic oceanic variations, and subtracted them from the observed OBP data. The numerical ocean models included four ocean general circulation models (OGCMs) of HYCOM, GLORYS, ECCO2, and JCOPE2M, and a single-layer ocean model (SOM). The OGCMs are mainly driven by the wind forcing. The SOM is driven by wind and/or atmospheric pressure loading. The modeled OBP was subtracted from the observed OBP data, and root-mean-square (RMS) amplitudes of the residual OBP variations at a period of 3{\textendash}90~days were evaluated by the respective regions and by the respective numerical ocean models. The OGCMs and SOM driven by wind alone (SOMw) contributed to 5{\textendash}27\% RMS reduction in the residual OBP. When SOM driven by atmospheric pressure alone (SOMp) was added to the modeled OBP, residual RMS amplitudes were additionally reduced by 2{\textendash}15\%. This indicates that the atmospheric pressure is necessary to explain substantial amounts of observed OBP variations at the period. The residual RMS amplitudes were 1.0{\textendash}1.7~hPa when SOMp was added. The RMS reduction was relatively effective as 16{\textendash}42\% at the Hikurangi Trough, the Nankai Trough, and the Japan Trench. The residual RMS amplitudes were relatively small as 1.0{\textendash}1.1~hPa at the Nankai Trough and the Chile Trench. These results were discussed with previous studies that had identified slow slips using OBP observations. We discussed on further accurate OBP modeling, and on improving detectability of seafloor deformation using OBP observation arrays.},
	issn = {2296-6463},
	doi = {10.3389/feart.2020.598270},
	url = {https://www.frontiersin.org/articles/10.3389/feart.2020.598270},
	author = {Dobashi, Yoichiro and Inazu, Daisuke}
}
@article {zhang_isotropic_2021,
	title = {Isotropic and azimuthally anisotropic Rayleigh wave dispersion across the Juan de Fuca and Gorda plates and U.S. Cascadia from earthquake data and ambient noise two- and three-station interferometry},
	journal = {Geophysical Journal International},
	volume = {226},
	number = {2},
	year = {2021},
	pages = {862{\textendash}883},
	abstract = {We use data from the Cascadia Initiative (CI) amphibious array and the USArray Transportable Array to construct and compare Rayleigh wave isotropic and azimuthally anisotropic phase speed maps across the Juan de Fuca and Gorda Plates extending onto the continental northwestern United States. Results from both earthquakes (28{\textendash}80~s) as well as ambient noise two- and three-station interferometry (10{\textendash}40~s) are produced. Compared with two-station interferometry, three-station direct wave interferometry provides \&gt;50~per~cent improvement in the signal-to-noise ratio and the number of dispersion measurements obtained, particularly in the noisier oceanic environment. Earthquake and ambient noise results are complementary in bandwidth and azimuthal coverage, and agree within about twice the estimated uncertainties of each method. We, therefore, combine measurements from the different methods to produce composite results that provide an improved data set in accuracy, resolution and spatial and azimuthal coverage over each individual method. A great variety of both isotropic and azimuthally anisotropic structures are resolved. Across the oceanic plate, fast directions of anisotropy with 180{\textdegree} periodicity (2ψ) generally align with palaeo-spreading directions while 2ψ amplitudes mostly increase with lithospheric age, both displaying substantial variations with depth and age. Strong (\&gt;3~per~cent) apparent anisotropy with 360{\textdegree} periodicity (1ψ) is observed at long periods (\&gt;50~s) surrounding the Cascade Range, probably caused by backscattering from heterogeneous isotropic structures.},
	issn = {0956-540X},
	doi = {10.1093/gji/ggab142},
	url = {https://doi.org/10.1093/gji/ggab142},
	author = {Zhang, Shane and Wang, Hongda and Wu, Mengyu and Ritzwoller, Michael H}
}
@article {Sheehan2019,
	title = {Improving Forecast Accuracy With Tsunami Data Assimilation: The 2009 Dusky Sound, New Zealand, Tsunami},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {124},
	number = {1},
	year = {2019},
	month = {jan},
	pages = {566{\textendash}577},
	issn = {2169-9313},
	doi = {10.1029/2018JB016575},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2018JB016575},
	author = {Sheehan, Anne F. and Gusman, Aditya R. and Satake, Kenji}
}
@article {Gong2018,
	title = {Interactions between strike-slip earthquakes and the subduction interface near the Mendocino Triple Junction},
	journal = {Earth and Planetary Science Letters},
	volume = {482},
	year = {2018},
	month = {jan},
	pages = {414{\textendash}422},
	issn = {0012821X},
	doi = {10.1016/j.epsl.2017.11.022},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0012821X17306581},
	author = {Gong, Jianhua and McGuire, Jeffrey J.}
}
@article {Tian2017,
	title = {Improving ambient noise cross-correlations in the noisy ocean bottom environment of the Juan de Fuca plate},
	journal = {Geophysical Journal International},
	volume = {210},
	number = {3},
	year = {2017},
	month = {sep},
	pages = {1787{\textendash}1805},
	issn = {0956-540X},
	doi = {10.1093/gji/ggx281},
	url = {https://academic.oup.com/gji/article/210/3/1787/3898835},
	author = {Tian, Ye and Ritzwoller, Michael H.}
}
@mastersthesis {Neale2017,
	title = {An investigation into ocean wave sources of ambient seismic noise},
	year = {2017},
	school = {University of Southampton},
	type = {phdPh.D.},
	url = {http://eprints.soton.ac.uk/id/eprint/412555},
	author = {Neale, J. F. W.}
}
@article {doran_infragravity_2016,
	title = {Infragravity waves and horizontal seafloor compliance},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {121},
	number = {1},
	year = {2016},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/2015JB012511},
	pages = {260{\textendash}278},
	abstract = {We report the first consistent observation of horizontal seafloor compliance induced by infragravity (IG) waves. Long-period IG ocean waves manifest themselves as broad, dominant features in ocean bottom pressure and vertical deformation spectra, but signals are rarely (if ever) identified on the horizontal components of traditional ocean bottom seismometers (OBS) due to low signal level and high current-induced tilt noise at long periods. We examine two OBS stations with shallow-buried seismometers: the Monterey Ocean Bottom Broadband site offshore California and the Ocean Seismic Network (OSN) pilot site OSN1B near Hawaii. We use nearby weather buoys to investigate the relationship between the presence of infragravity waves and environmental conditions. We find strong evidence that infragravity wave generation is primarily confined to the near-coastal environment. Additional IG source information is found by examining the directionality of passing IG waves as a function of frequency, which we analyze using the coherence between pressure and the two horizontal components. Finally, we evaluate the implications for a joint vertical and horizontal compliance inversion.},
	keywords = {horizontal infragravity energy, horizontal seafloor compliance},
	issn = {2169-9356},
	doi = {10.1002/2015JB012511},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2015JB012511},
	author = {Doran, Adrian K. and Laske, Gabi}
}
@article {Harris2016,
	title = {Investigations of Shallow Slow Slip Offshore of New Zealand},
	journal = {Eos},
	volume = {97},
	year = {2016},
	month = {mar},
	abstract = {Recent and upcoming studies of the Hikurangi margin east of New Zealand shed light on previously undetectable tectonic movements.},
	issn = {2324-9250},
	doi = {10.1029/2016EO048945},
	url = {https://eos.org/project-updates/investigations-of-shallow-slow-slip-offshore-of-new-zealand},
	author = {Harris, Robert and Wallace, Laura and Webb, Spahr and Ito, Yoshihiro and Mochizuki, Kimihiro and Ichihara, Hiroshi and Henrys, Stuart and Tr{\'e}hu, Anne and Schwartz, Susan and Sheehan, Anne and Saffer, Demian and Lauer, Rachel}
}
@article {Wang2016,
	title = {Invited review paper: Some outstanding issues in the study of great megathrust earthquakes{\textemdash}The Cascadia example},
	journal = {Journal of Geodynamics},
	volume = {98},
	year = {2016},
	month = {aug},
	pages = {1{\textendash}18},
	issn = {02643707},
	doi = {10.1016/j.jog.2016.03.010},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S026437071530017X},
	author = {Wang, Kelin and Tr{\'e}hu, Anne M.}
}
@article {Janiszewski2015,
	title = {Imaging the Plate Interface in the Cascadia Seismogenic Zone: New Constraints from Offshore Receiver Functions},
	journal = {Seismological Research Letters},
	volume = {86},
	number = {5},
	year = {2015},
	month = {sep},
	pages = {1261{\textendash}1269},
	issn = {0895-0695},
	doi = {10.1785/0220150104},
	url = {https://pubs.geoscienceworld.org/srl/article/86/5/1261-1269/315535},
	author = {Janiszewski, Helen A. and Abers, Geoffrey A.}
}
@article {froment_imaging_2014,
	title = {Imaging along-strike variations in mechanical properties of the Gofar transform fault, East Pacific Rise},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {119},
	number = {9},
	year = {2014},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/2014JB011270},
	pages = {7175{\textendash}7194},
	abstract = {AbstractA large part of global plate motion on mid-ocean ridge transform faults (RTFs) is not accommodated as major earthquakes. When large earthquakes do occur, they often repeat quasiperiodically. We focus here on the high slip rate (\~{}14 cm/yr) Gofar transform fault on the equatorial East Pacific Rise. This fault is subdivided into patches that slip during Mw 5.5{\textendash}6 earthquakes every 5 to 6 years. These patches are separated by rupture barriers that accommodate slip through swarms of smaller events and/or aseismic creep. We performed an imaging study to investigate which spatiotemporal variations of the fault zone properties control this segmentation in mechanical behavior and could explain the specific behavior of RTFs at the global scale. We adopt a double-difference approach in a joint inversion of active air gun shots and microseismicity recorded for 1 year. This data set includes the 2008 Mw 6 Gofar earthquake. The along-strike P wave velocity structure reveals an abrupt transition between the barrier area, characterized by a damaged fault zone of 10{\textendash}20\% reduced Vp and a nearly intact fault zone in the asperity area. The importance of the strength of the damage zone on the mechanical behavior is supported by the temporal S wave velocity changes which suggest increased damage within the barrier area, during the week preceding the Mw 6 earthquake. Our results support the conclusion that extended highly damaged zones are the key factor in limiting the role of major earthquakes to accommodate plate motion along RTFs.},
	keywords = {double-difference tomography, fault zone, imaging, mid-ocean ridge transform fault},
	issn = {2169-9356},
	doi = {10.1002/2014JB011270},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2014JB011270},
	author = {Froment, B. and McGuire, J. J. and van der Hilst, R. D. and Gou{\'e}dard, P. and Roland, E. C. and Zhang, H. and Collins, J. A.}
}
@article {godin_interferometry_2014,
	title = {Interferometry of infragravity waves off New Zealand},
	journal = {Journal of Geophysical Research: Oceans},
	volume = {119},
	number = {2},
	year = {2014},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/2013JC009395},
	pages = {1103{\textendash}1122},
	abstract = {AbstractWave interferometry is a remote sensing technique, which is increasingly employed in helioseismology, seismology, and acoustics to retrieve parameters of the propagation medium from two-point cross-correlation functions of random wavefields. Here we apply interferometry to yearlong records of seafloor pressure at 28 locations off New Zealand{\textquoteright}s South Island to investigate propagation and directivity properties of infragravity waves away from shore. A compressed cross-correlation function technique is proposed to make the interferometry of dispersive waves more robust, decrease the necessary noise averaging time, and simplify retrieval of quantitative information from noise cross correlations. The emergence of deterministic wave arrivals from cross correlations of random wavefields is observed up to the maximum range of 692 km between the pressure sensors in the array. Free, linear waves with a strongly anisotropic distribution of power flux density are found to be dominant in the infragravity wavefield. Lowest-frequency components of the infragravity wavefield are largely isotropic. The anisotropy has its maximum in the middle of the spectral band and decreases at the high-frequency end of the spectrum. Highest anisotropy peaks correspond to waves coming from portions of the New Zealand{\textquoteright}s shoreline. Significant contributions are also observed from waves propagating along the coastline and probably coming from powerful sources in the northeast Pacific. Infragravity wave directivity is markedly different to the east and to the west of the South Island. The northwest coast of the South Island is found to be a net source of the infragravity wave energy.},
	keywords = {deep ocean, random wave fields, Surface gravity waves, wave interferometry},
	issn = {2169-9291},
	doi = {10.1002/2013JC009395},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2013JC009395},
	author = {Godin, Oleg A. and Zabotin, Nikolay A. and Sheehan, Anne F. and Collins, John A.}
}
@article {mcintosh_inversion_2013,
	title = {Inversion of a hyper-extended rifted margin in the southern Central Range of Taiwan},
	journal = {Geology},
	volume = {41},
	number = {8},
	year = {2013},
	month = {aug},
	pages = {871{\textendash}874},
	abstract = {Seismic reflection and wide-angle data acquired across, south, and west of Taiwan show that extended to hyper-extended continental crust of the Chinese continental margin is present more than 200 km south of the shelf and is subducting at the Manila Trench. Furthermore, crustal-scale tomographic velocity models show that this crust is underthrusted to \~{}15 km depth below the accretionary prism, where it then is structurally underplated to the base of the prism. We document an increasing volume of accreted crust from south to north, and in our northern transect high-velocity material of the accretionary prism can be directly linked to outcrops of Central Range basement rocks. In map view the Central Range of Taiwan is clearly contiguous with the Hengchun Peninsula and Hengchun submarine ridge to the south. Accordingly, we propose a new model in which the Central Range forms directly from the accretionary prism, including the basement core, which originates from subducted, and then accreted, extended to hyper-extended continental crust.},
	issn = {0091-7613},
	doi = {10.1130/G34402.1},
	url = {https://doi.org/10.1130/G34402.1},
	author = {McIntosh, Kirk and van Avendonk, Harm and Lavier, Luc and Lester, W. Ryan and Eakin, Daniel and Wu, Francis and Liu, Char-Shine and Lee, Chao-Shing}
}
@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 {okaya_imaging_2003,
	title = {Imaging a plate boundar using double-sided onshore-offshore seismic profiling},
	journal = {The Leading Edge},
	volume = {22},
	number = {3},
	year = {2003},
	month = {mar},
	pages = {256{\textendash}260},
	issn = {1070-485X},
	doi = {10.1190/1.1564531},
	url = {https://doi.org/10.1190/1.1564531},
	author = {Okaya, David and Stern, Tim and Holbrook, Steve and van Avendonk, Harm and Davey, Fred and Henrys, Stuart}
}
