@article {trehu_deformation_2023,
	title = {Deformation of the Juan de Fuca Plate Beneath the Central Cascadia Continental Margin (44{\textdegree}-45{\textdegree}N) in Response to an Upper Plate Load},
	journal = {Earth Science, Systems and Society},
	volume = {3},
	year = {2023},
	note = {Publisher: Frontiers},
	month = {11/2023},
	pages = {10085},
	abstract = {A 3D crustal model for the central Cascadia continental shelf and Coast Range between 44{\textdegree}N and 45{\textdegree}N shows that the crystalline crust of the forearc wedge beneath the coastline is characterized by a NW-trending, vertical slab of high-velocity rock interpreted to represent the dike complex that fed the Yachats basaltsBasalt, which werewas intruded into the forearc approximately 3637 million years ago. A spatial correlation is observed between downward deflection of the crust of the subducting Juan de Fuca plate, inferred from inversion of PmP arrivals to image the Moho surface, and the high velocity (and consequently high density) dike complex.anomaly underlying the Yachats Basalt. Apparent subsequent rebound of the subducting plate at greater depth suggests a primarily elastic response of the subducting plate to this load. Calculations for a range of plausible values for the magnitude of the load and the width and depth of the depression indicate that that the effective elastic thickness of the subducted Juan de Fuca plate is \textasciitilde2-<6 km. Although our simple analytical models do not include partial support of the load of the slab by the adjacent upper plate crust or time dependence to account for the motion of the slab beneath the load, incorporation of those effects should decrease rather than increase the apparent strength of the subducted plate. We conclude that the subducted Juan de Fuca plate beneath the central Oregon margin is elastically thin and has the potential to store elastic strain energy before rupturing. Our model of a well-defined, focused and static upper plate load that locally deforms the subducted plate within the nominally seismogenic or transitional part of the Cascadia plate boundary may be unique in providing a relatively straightforward scenario for estimating the mechanical properties of the subducted Juan de Fuca plate. We extrapolate from these results to speculate that elastic deformation of the subducting plate may contribute to the low level of seismicity throughout much of the Cascadia forearc in inter-seismic period between great earthquakes but note that our local results do not preclude faulting or elasto-plastic deformation of a thin and weak plate as it subducts.},
	issn = {2634-730X},
	doi = {10.3389/esss.2023.10085},
	url = {https://www.escubed.org/articles/10.3389/esss.2023.10085/full},
	author = {Tr{\'e}hu, Anne M. and Davenport, Kathy and Kenyon, Christopher B. and Carbotte, Suzanne M. and N{\'a}b{\v e}lek, John L. and Toomey, Douglas R. and Wilcock, William S. D.}
}
@article {wilcock_method_2021,
	title = {A method for tracking blue whales (Balaenoptera musculus) with a widely spaced network of ocean bottom seismometers},
	journal = {PLOS ONE},
	volume = {16},
	number = {12},
	year = {2021},
	note = {Publisher: Public Library of Science},
	month = {dec},
	pages = {e0260273},
	abstract = {Passive acoustic monitoring is an important tool for studying marine mammals. Ocean bottom seismometer networks provide data sets of opportunity for studying blue whales (Balaenoptera musculus) which vocalize extensively at seismic frequencies. We describe methods to localize calls and obtain tracks using the B call of northeast Pacific blue whale recorded by a large network of widely spaced ocean bottom seismometers off the coast of the Pacific Northwest. The first harmonic of the B call at \textasciitilde15 Hz is detected using spectrogram cross-correlation. The seasonality of calls, inferred from a dataset of calls identified by an analyst, is used to estimate the probability that detections are true positives as a function of the strength of the detection. Because the spacing of seismometers reaches 70 km, faint detections with a significant probability of being false positives must be considered in multi-station localizations. Calls are located by maximizing a likelihood function which considers each strong detection in turn as the earliest arrival time and seeks to fit the times of detections that follow within a feasible time and distance window. An alternative procedure seeks solutions based on the detections that maximize their sum after weighting by detection strength and proximity. Both approaches lead to many spurious solutions that can mix detections from different B calls and include false detections including misidentified A calls. Tracks that are reliable can be obtained iteratively by assigning detections to localizations that are grouped in space and time, and requiring groups of at least 20 locations. Smooth paths are fit to tracks by including constraints that minimize changes in speed and direction while fitting the locations to their uncertainties or applying the double difference relocation method. The reliability of localizations for future experiments might be improved by increasing sampling rates and detecting harmonics of the B call.},
	keywords = {Blue whales, Fin whales, Latitude, Longitude, Marine mammals, Oceans, Probability density, Whales},
	issn = {1932-6203},
	doi = {10.1371/journal.pone.0260273},
	url = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0260273},
	author = {Wilcock, William S. D. and Hilmo, Rose S.}
}
@article {115,
	title = {Physical Sources of High-Frequency Seismic Noise on Cascadia Initiative Ocean Bottom Seismometers},
	journal = {Geochemistry Geophysics Geosystems},
	volume = {21},
	year = {2020},
	type = {Journal Article},
	abstract = {Physical sources of high-frequency seismic noise in the ocean are investigated using data from the Cascadia Initiative (CI) ocean bottom seismometer (OBS) network, hindcasts of wind speed, waves, and the bottom currents predicted by a regional ocean circulation model and observed at sites on cabled observatories. Seismic data in the 5{\textendash}12 Hz band are considered because it is best for detecting regional earthquakes and lies between the frequencies of local microseisms and the seasonal whale calls. Median noise levels in this range vary by ~20 dB between sites at a given depth but on average decrease with increasing depth. On the continental shelf, the orbital motions of ocean waves are a major source of noise while at the quietest sites in the deep ocean, noise increases when wind speeds exceed ~10 m/s. On the continental slope and abyssal plain within about 100 km of the slope, seismic noise is not predicted at specific sites by the bottom currents in the ocean circulation model. In these regions, ocean currents are inferred to be the primary source of noise, because noise varies on tidal periods, is low on buried seismometers, and has spatial variations broadly consistent with those of median absolute currents. Comparisons between OBSs suggest that high-frequency noise is reduced by low-profile hydrodynamic designs but not by shielding. Many OBSs also record numerous short duration events on and near the continental shelf that have been attributed elsewhere to animals bumping into the sensor or gas bubbles moving through sediments. Environmental noise generated by waves, wind, and ocean currents limits the ability of seafloor seismometers to detect the ground motions from earthquakes. This research uses data from a large deployment of seafloor seismometers off the coast of the Pacific Northwest of America to understand the seismic noise at frequencies of 5{\textendash}12 Hz which coincides with the frequency band used to detect regional earthquakes. Instruments deployed in shallow water on the continental shelf record high noise levels caused by motions from ocean waves that reach the seafloor. The quietest sites are found in the deep ocean far from the coast, and here the noise is created by wind blowing spray from whitecaps. At intermediate sites on the continental slope and deep ocean just seaward of the continental slope, the noise results from ocean currents that are related to ocean circulation and tides. Some shallow instruments also record large numbers of short signals that are not earthquakes and may be either a result of animals bumping into the seismic sensor or gas bubbles moving through sediments. The best way to reduce seismic noise is to bury the seismic sensors, but when this is infeasible, the instruments should have a short hydrodynamic design. Seismic noise is high on the shelf due to wave orbital currents, and noise at the quietest abyssal plain sites is correlated with wind speed Ocean currents are the primary source of high-frequency noise on the continental slope and abyssal plain within ~100 km of the slope High-frequency current-generated seismic noise is reduced on OBSs with squat hydrodynamic designs and is not clearly reduced by shielding.},
	doi = {10.1029/2020gc009085},
	url = {https://app.dimensions.ai/details/publication/pub.1131195022},
	author = {Hilmo, Rose and Wilcock, William S. D.}
}
@article {fredrickson_optimizing_2019,
	title = {Optimizing Sensor Configurations for the Detection of Slow-Slip Earthquakes in Seafloor Pressure Records, Using the Cascadia Subduction Zone as a Case Study},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {124},
	number = {12},
	year = {2019},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2019JB018053},
	pages = {13504{\textendash}13531},
	abstract = {We present seafloor pressure records from the Cascadia Subduction Zone, alongside oceanographic and geophysical models, to evaluate the spatial uniformity of bottom pressure and optimize the geometry of sensor networks for resolving offshore slow-slip transients. Seafloor pressure records from 2011 to 2015 show that signal amplitudes are depth-dependent, with tidally filtered and detrended root-mean-squares of <2 cm on the abyssal plain and >6 cm on the continental shelf. This is consistent with bottom pressure predictions from circulation models and comparable to deformation amplitudes from offshore slow slip observed in other subduction zones. We show that the oceanographic component of seafloor pressure can be reduced to <=1-cm root-mean-square by differencing against a reference record from a similar depth, under restrictions that vary with depth. Instruments at 100{\textendash}250 m require depths matched within 10 m at separations of <100 km, while locations deeper than 1,400 m are broadly comparable over separations of at least 300 km. Despite the significant noise reduction from this method, no slow slip was identified in the dataset, possibly due to poor spatiotemporal instrument coverage, nonideal deployment geometry, and limited depth-matched instruments. We use forward predictions of deformation from elastic half-space models and hindcast pressure from circulation models to generate synthetic slow-slip observational records and show that a range of slip scenarios produce resolvable signals under depth-matched differencing. For future detection of offshore slow slip in Cascadia, we recommend a geometry in which instruments are deployed along isobaths to optimize corrections for oceanographic signals.},
	keywords = {Cascadia Subduction Zone, geodesy, ocean circulation, seafloor pressure, slow-slip earthquake},
	issn = {2169-9356},
	doi = {10.1029/2019JB018053},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019JB018053},
	author = {Fredrickson, Erik K. and Wilcock, William S. D. and Schmidt, David A. and MacCready, Parker and Roland, Emily and Kurapov, Alexander L. and Zumberge, Mark A. and Sasagawa, Glenn S.}
}
@article {Kim2018,
	title = {Upper crustal Vp / Vs ratios at the Endeavour segment, Juan de Fuca Ridge, from joint inversion of P and S travel times: Implications for hydrothermal circulation},
	journal = {Geochemistry, Geophysics, Geosystems},
	year = {2018},
	month = {dec},
	pages = {2018GC007921},
	issn = {1525-2027},
	doi = {10.1029/2018GC007921},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2018GC007921},
	author = {Kim, Eunyoung and Toomey, Douglas R. and Hooft, Emilie E. E. and Wilcock, William S. D. and Weekly, Robert T. and Lee, Sang-Mook and Kim, Young Hee}
}
@article {Kim2018a,
	title = {Upper crustal Vp / Vs ratios at the Endeavour segment, Juan de Fuca Ridge, from joint inversion of P and S travel times: Implications for hydrothermal circulation},
	journal = {Geochemistry, Geophysics, Geosystems},
	year = {2018},
	month = {dec},
	pages = {2018GC007921},
	issn = {1525-2027},
	doi = {10.1029/2018GC007921},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2018GC007921},
	author = {Kim, Eunyoung and Toomey, Douglas R. and Hooft, Emilie E. E. and Wilcock, William S. D. and Weekly, Robert T. and Lee, Sang-Mook and Kim, Young Hee}
}
@article {Weirathmueller2017,
	title = {Estimating range to a vocalizing fin whale using the timing and amplitude of multipath arrivals},
	journal = {The Journal of the Acoustical Society of America},
	volume = {142},
	number = {4},
	year = {2017},
	month = {oct},
	pages = {2101{\textendash}2120},
	issn = {0001-4966},
	doi = {10.1121/1.5005494},
	url = {http://asa.scitation.org/doi/10.1121/1.5005494},
	author = {Weirathmueller, Michelle J. and Wilcock, William S. D. and Hilmo, Rose S.}
}
@article {Arnoux2017,
	title = {Seismic evidence that black smoker heat flux is influenced by localized magma replenishment and associated increases in crustal permeability},
	journal = {Geophysical Research Letters},
	volume = {44},
	number = {4},
	year = {2017},
	month = {feb},
	pages = {1687{\textendash}1695},
	issn = {00948276},
	doi = {10.1002/2016GL071990},
	url = {http://doi.wiley.com/10.1002/2016GL071990},
	author = {Arnoux, Gillean M. and Toomey, Douglas R. and Hooft, Emilie E. E. and Wilcock, William S. D. and Morgan, Joanna and Warner, Mike and VanderBeek, Brandon P.}
}
@article {Weirathmueller2017a,
	title = {Spatial and temporal trends in fin whale vocalizations recorded in the NE Pacific Ocean between 2003-2013},
	journal = {PLOS ONE},
	volume = {12},
	number = {10},
	year = {2017},
	month = {oct},
	pages = {e0186127},
	issn = {1932-6203},
	doi = {10.1371/journal.pone.0186127},
	url = {https://dx.plos.org/10.1371/journal.pone.0186127},
	author = {Weirathmueller, Michelle J. and Stafford, Kathleen M. and Wilcock, William S. D. and Hilmo, Rose S. and Dziak, Robert P. and Tr{\'e}hu, Anne M.},
	editor = {Li, Songhai}
}
@article {Soule2016,
	title = {Near-axis crustal structure and thickness of the Endeavour Segment, Juan de Fuca Ridge},
	journal = {Geophysical Research Letters},
	volume = {43},
	number = {11},
	year = {2016},
	month = {jun},
	pages = {5688{\textendash}5695},
	issn = {00948276},
	doi = {10.1002/2016GL068182},
	url = {http://doi.wiley.com/10.1002/2016GL068182},
	author = {Soule, Dax and Wilcock, William S. D. and Toomey, Douglas R. and Hooft, Emilie E. E. and Weekly, Robert T.}
}
@article {VanderBeek2016,
	title = {Segmentation of mid-ocean ridges attributed to oblique mantle divergence},
	journal = {Nature Geoscience},
	volume = {9},
	number = {8},
	year = {2016},
	month = {aug},
	pages = {636{\textendash}642},
	issn = {1752-0894},
	doi = {10.1038/ngeo2745},
	url = {http://www.nature.com/articles/ngeo2745},
	author = {VanderBeek, Brandon P. and Toomey, Douglas R. and Hooft, Emilie E. E. and Wilcock, William S. D.}
}
