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Crustal block-controlled contrasts in deformation, uplift, and exhumation in the Santa Cruz Mountains, California, USA, imaged through apatite (U-Th)/He thermochronology and 3-D geological modeling

Deformation along strike-slip plate margins often accumulates within structurally partitioned and rheologically heterogeneous crustal blocks within the plate boundary. In these cases, contrasts in the physical properties and state of juxtaposed crustal blocks may play an important role in accommodation of deformation. Near the San Francisco Bay Area, California, USA, the Pacific−North American pla
Curtis William Baden, David L. Shuster, Jeremy H. Hourigan, Jared T. Gooley, Melanie Cahill, George E. Hilley

Crustal thickness and the VP/VS ratio within the Arabia Plate from P-wave receiver functions at 154 broadband seismic stations

As part of a joint Saudi Geological Survey (SGS) and United States Geological Survey project, we analyzed P-wave receiver functions from seismic stations covering most of the Kingdom of Saudi Arabia to map the thickness of the crust across the Arabia Plate. We present an update of crustal thickness estimates and fill in gaps for the western Arabian Shield and the rifted margin at the Red Sea (the
Alexander R. Blanchette, Simon L. Klemperer, Walter D. Mooney

Shallow fault slip of the 2020 M5.1 Sparta, North Carolina, earthquake

The 2020 M 5.1 Sparta, North Carolina, earthquake is the largest in the eastern United States since the 2011 M 5.8 Mineral, Virginia, earthquake and produced a ∼2.5‐km‐long surface rupture, unusual for an event of this magnitude. A geological field study conducted soon after the event indicates oblique slip along a east‐southeast‐trending fault with a consistently observed thrust component. My ana
Fred Pollitz

Summary of the history and research of the U.S. Geological Survey gas hydrate properties laboratory in Menlo Park, California, active from 1993 to 2022

The U.S. Geological Survey (USGS) Clathrate Hydrate Properties Project, active from 1993 to 2022 in Menlo Park, California, stemmed from an earlier project on the properties of planetary ices supported by the National Aeronautics and Space Administration’s (NASA’s) Planetary Geology and Geophysics Program. We took a material science approach in both projects, emphasizing chemical purity of samples
Laura A. Stern, Stephen H. Kirby

Quantifying site effects and their influence on earthquake source parameter estimations using a dense array in Oklahoma

We investigate the effects of site response on source parameter estimates using earthquakes recorded by the LArge-n Seismic Survey in Oklahoma (LASSO). While it is well known that near-surface unconsolidated sediments can cause an apparent breakdown of earthquake self-similarity, the influence of laterally varying site conditions remains unclear. We analyze site conditions across the 1825-station
Hilary Chang, Rachel E. Abercrombie, Nori Nakata, Colin Pennington, Kilian B. Kemna, Elizabeth S. Cochran, Rebecca M. Harrington

Seismic images and subsurface structures of northeastern Edwards Air Force Base, Kern County, California

We used multi-component seismic data (including two-dimensional images of compressional-wave velocity [vP], shear-wave velocity [vS], the ratio of compressional-wave velocity to shear-wave velocity [vP/vS ratio], Poisson’s ratio [μ], and seismic reflections) along a transect across northeastern Edwards Air Force Base to investigate the upper few hundred meters of the subsurface. The shallow subsur
Rufus D. Catchings, Mark R. Goldman, Joanne H. Chan, Robert R. Sickler, Coyn J. Criley

Ground‐motion variability from kinematic rupture models and the implications for nonergodic probabilistic seismic hazard analysis

The variability of earthquake ground motions has a strong control on probabilistic seismic hazard analysis (PSHA), particularly for the low frequencies of exceedance used for critical facilities. We use a crossed mixed‐effects model to partition the variance components from simulated ground motions of Mw 7 earthquakes on the Salt Lake City segment of the Wasatch fault zone. Total variability of si
Grace Alexandra Parker, Morgan P. Moschetti, Eric M. Thompson

Comparison of earthquake early warning systems and the national volcano early warning system at the U.S. Geological Survey

IntroductionEvery year in the United States, natural hazards threaten lives and livelihoods, resulting in thousands of casualties and billions of dollars in damage. The U.S. Geological Survey (USGS) Natural Hazards Mission Area works with many partners to monitor, assess, and research a wide range of natural hazards, including earthquakes and volcanic eruptions. These efforts aim to enhance commun
Aleeza Wilkins, Charlie Mandeville, John Power, Doug Given

Scaling microseismic cloud shape during hydraulic stimulation using in-situ stress and permeability

Forecasting microseismic cloud shape as a proxy of stimulated rock volume may improve the design of an energy extraction system. The microseismic cloud created during hydraulic stimulation of geothermal reservoirs is known empirically to extend in the general direction of the maximum principal stress. However, this empirical relationship is often inconsistent with reported results, and the cloud g
Y. Mukuhira, M. Yang, T. Ishibashi, K. Okamoto, H. Moriya, Y. Kumano, H. Asanuma, S.A. Shapiro, Justin Rubinstein, T. Ito, K. Yan, Y. Zuo

Converted-wave reverse time migration imaging in subduction zone settings

We use a newly developed 2-D elastic reverse time migration (RTM) imaging algorithm based on the Helmholtz decomposition to test approaches for imaging the descending slab in subduction zone regions using local earthquake sources. Our elastic RTM method is designed to reconstruct incident and scattered wavefields at depth, isolate constituent P- and S-wave components via Helmholtz decomposition, a
Leah Langer, Fred Pollitz, Jeffrey McGuire

Accuracy of finite fault slip estimates in subduction zone regions with topographic Green's functions and seafloor geodesy

Until recently, the lack of seafloor geodetic instrumentation and the use of unrealistically simple, half-space based forward models have resulted in poor resolution of near-trench slip in subduction zone settings. Here, we use a synthetic framework to investigate the impact of topography and geodetic data distribution on coseismic slip estimates in various subduction zone settings. We calculate s
Leah Langer, Théa Ragon

Slip deficit rates on southern Cascadia faults resolved with viscoelastic earthquake cycle modeling of geodetic deformation

The fore‐arc of the southern Cascadia subduction zone (CSZ), north of the Mendocino triple junction (MTJ), is home to a network of Quaternary‐active crustal faults that accumulate strain due to the interaction of the North American, Juan de Fuca (Gorda), and Pacific plates. These faults, including the Little Salmon and Mad River fault (LSF and MRF) zones, are located near the most populated parts
Kathryn Zerbe Materna, Jessica R. Murray, Fred Pollitz, Jason R. Patton