@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 {alongi_probing_2021,
	title = {Probing the Southern Cascadia Plate Interface With the Dense Amphibious Cascadia Initiative Seismic Array},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {126},
	number = {7},
	year = {2021},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2021JB022180},
	month = {06/2021},
	pages = {e2021JB022180},
	abstract = {Fault coupling is vital in determining the amount of strain that is accumulated along faults. The magnitude and location of stored elastic strain energy in highly coupled regions has important implications for understanding the full range of slip behavior at plate boundary faults, as well as earthquake and tsunami hazards. We use the temporary dense amphibious array of seismometers offered by the Cascadia Initiative to create a high-resolution catalog of events to examine the spatio-temporal behavior of earthquakes near the plate interface. The data show that in southern Cascadia the plate interface updip of the geodetically locked region is nearly devoid of seismicity, therefore likely highly coupled and accumulating strain. The catalog reveals events that are clustered at the downdip edge of the highly coupled megathrust that correlate in time with nearby strain transient observations. Template matching of events in the cluster using permanent stations of the Northern California Seismic Network over a 10-year period between 2010 and 2020 indicates that this cluster is unique in space and time. Its activity only during the strain transient provides support for the utility of seismic observations in the identification of strain transients.},
	keywords = {microseismicity, ocean bottom seismometers, plate interface, seismology, strain transient, template matching},
	issn = {2169-9356},
	doi = {10.1029/2021JB022180},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2021JB022180},
	author = {Alongi, T. and Schwartz, S. Y. and Shaddox, H. R. and Small, D. T.}
}
@article {heath_relationship_2021,
	title = {Relationship Between Active Faulting/Fracturing and Magmatism Around Santorini: Seismic Anisotropy From an Active Source Tomography Experiment},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {126},
	number = {8},
	year = {2021},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2021JB021898},
	month = {07/2021},
	pages = {e2021JB021898},
	abstract = {In extending volcanic arcs such as the Aegean, tectonic processes exert a significant control on magmatism. Spanning scales from 1 to 10s of km, volcanic vents, edifices, and eruptive centers follow the orientation of, and are located near, fault zones. Whether this tectonic control on magmatism results from individual faults/fractures weakening the crust or because regional stresses control magma input into the crust is debated. Here we investigate the scales of tectonic and magmatic interactions, specifically focusing on the role of local-scale (<10 km) faults/fractures in controlling magmatism. We infer local-scale fault/fracture orientations from anisotropic active-source P-wave travel-time tomography to investigate tectonic and magmatic interactions in the upper crust of Santorini Volcano, Greece, and the actively deforming region to the east. We use the anisotropy magnitude and seismic velocity reduction to model the relative distribution of both consistently oriented and randomly oriented faults/fractures. Our results show that oriented faulting/fracturing resulting from regional-scale (>10 km) tectonic stresses is distributed broadly across the region at 2{\textendash}3 km depth, approximately paralleling volcanic/magmatic features. On a local-scale, magmatism is neither localized in areas of higher oriented fault/fracture density, nor is it accommodating enough extensional strain to inhibit oriented faulting/fracturing of host rock. The alignment of magmatic features shows strong tectonic control despite the lack of correlation with local oriented fault/fracture density. These results suggest that magmatic processes are strongly influenced by regional-scale, not local-scale, tectonic processes. We infer regional processes have a greater impact on magmatism than local features due to their greater effect at depth.},
	keywords = {anisotropy, faulting, magmatism, seismology, tectonism, tectono-magmatism},
	issn = {2169-9356},
	doi = {10.1029/2021JB021898},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2021JB021898},
	author = {Heath, B. A. and Hooft, E. E. E. and Toomey, D. R. and Paulatto, M. and Papazachos, C. B. and Nomikou, P. and Morgan, J. V.}
}
@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 {warren-smith_episodic_2019,
	title = {Episodic stress and fluid pressure cycling in subducting oceanic crust during slow slip},
	journal = {Nature Geoscience},
	volume = {12},
	number = {6},
	year = {2019},
	note = {Number: 6 Publisher: Nature Publishing Group},
	month = {jun},
	pages = {475{\textendash}481},
	abstract = {Slow slip events are part of a spectrum of aseismic processes that relieve tectonic stress on faults. Their spatial distribution in subduction zones has been linked to perturbations in fluid pressure within the megathrust shear zone and subducting oceanic crust. However, physical observations of temporal fluid pressure fluctuations through slow slip cycles remain elusive. Here, we use earthquake focal mechanisms recorded on an ocean-bottom seismic network to show that crustal stresses and fluid pressures within subducting oceanic crust evolve before and during slow slip events. Specifically, we observe that the retrieved stress ratio, which describes the relative magnitudes of the principal compressive stresses, systematically decreases before slow slip events in New Zealand{\textquoteright}s northern Hikurangi subduction zone, and subsequently increases during the evolution of each slow slip event. We propose that these changes represent the accumulation and release of fluid pressure within overpressured subducting oceanic crust, the episodicity of which may influence the timing of slow slip event occurrence on subduction megathrusts. This work contributes an improved understanding of the physical driving forces underlying slow subduction earthquakes, and a potential means by which to monitor stress and fluid pressure accumulation in such regions.},
	keywords = {seismology, Tectonics},
	issn = {1752-0908},
	doi = {10.1038/s41561-019-0367-x},
	url = {https://www.nature.com/articles/s41561-019-0367-x},
	author = {Warren-Smith, E. and Fry, B. and Wallace, L. and Chon, E. and Henrys, S. and Sheehan, A. and Mochizuki, K. and Schwartz, S. and Webb, S. and Lebedev, S.}
}
@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 {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 {dunn_contrasting_2011,
	title = {Contrasting crustal production and rapid mantle transitions beneath back-arc ridges},
	journal = {Nature},
	volume = {469},
	number = {7329},
	year = {2011},
	note = {Number: 7329 Publisher: Nature Publishing Group},
	pages = {198{\textendash}202},
	abstract = {The Eastern Lau spreading centre, located on the Lau back-arc basin hydrothermal vent system between Fiji and Tonga, is a focus site of the Ridge 2000 research programme of the US National Science Foundation. The first large-scale seismic study of the area reveals large and abrupt across- and along-strike changes in crustal properties, implying correspondingly large discontinuities in the nature of the mantle supplying melt to the ridge axes. The authors conclude that stable, broad triangular upwelling regions, as inferred for mid-ocean ridges, cannot form near the mantle wedge corner. Instead, the observations imply a dynamic process in which the ridge upwelling zone preferentially captures water-rich low-viscosity mantle when it is near the arc. As the ridge moves away from the arc, a tipping point is reached at which the material is rapidly released, resulting in rapid changes in the character of the crust formed at the ridge.},
	keywords = {seismology},
	issn = {1476-4687},
	doi = {10.1038/nature09690},
	url = {https://www.nature.com/articles/nature09690},
	author = {Dunn, Robert A. and Martinez, Fernando}
}
