Publications
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Length-scale-dependent relationships between VS30 and topographic slopes in southern California Length-scale-dependent relationships between VS30 and topographic slopes in southern California
In engineering seismology, the time‐averaged shear‐wave velocity (VS) of the upper 30 m of the crust (VS30) is the primary parameter used in ground‐motion models to predict seismic site effects. VS30 is typically derived from in situ recordings of VS, although proxy‐based approaches (using geologic and/or geomorphometric classifications) are provisionally adopted when measurement...
Authors
Jessica Lin, Seulgi Moon, Alan Yong, Lingseng Meng, Paul Davies
κ0 and broadband site spectra in Southern California from source model-constrained inversion κ0 and broadband site spectra in Southern California from source model-constrained inversion
Ground-motion modeling requires accurate representation of the earthquake source, path, and site. Site amplification is often modeled by VS30, the time-averaged shear-wave velocity of the top 30 meters of the Earth’s surface, though recent studies find that its ability to accurately predict site effects varies. Another measure of the site is κ0, the attenuation of high frequency energy...
Authors
Alexis Klimasewski, Valerie J. Sahakian, Annemarie S. Baltay Sundstrom, John Boatwright, Jon Peter Fletcher, Lawrence Baker
Regional Global Navigation Satellite System networks for crustal deformation monitoring Regional Global Navigation Satellite System networks for crustal deformation monitoring
Regional networks of Global Navigation Satellite System (GNSS) stations cover seismically and volcanically active areas throughout the United States. Data from these networks have been used to produce high‐precision, three‐component velocity fields covering broad geographic regions as well as position time series that track time‐varying crustal deformation. This information has...
Authors
Jessica R. Murray, Noel Bartlow, Yehuda Bock, Benjamin A. Brooks, James H. Foster, Jeffery T. Freymueller, William C. Hammond, Kathleen Hodgkinson, Ingrid A. Johanson, Alberto Lopez-Venegas, Doerte Mann, Glen Mattioli, Timothy Melbourne, David Mencin, Emily K. Montgomery-Brown, Mark Hunter Murray, Robert Smalley, Valerie Thomas
Temporal patterns of induced seismicity in Oklahoma revealed from multi-station template matching Temporal patterns of induced seismicity in Oklahoma revealed from multi-station template matching
Over the past decade, Oklahoma became the most seismically active region of the mid-Continental USA as a result of industry operations. However, seismic network limitations and completeness of earthquake catalogs have restricted the types of analyses that can be performed. By applying multi-station template matching on the 23,889 cataloged earthquakes in Oklahoma and Southern Kansas...
Authors
Robert J. Skoumal, Michael R. Brudzinski, Brian S. Currie, Rosamiel Ries
Characterizing and imaging sedimentary strata using depth-converted spectral ratios: An example from the Atlantic Coastal Plain of the Eastern U.S. Characterizing and imaging sedimentary strata using depth-converted spectral ratios: An example from the Atlantic Coastal Plain of the Eastern U.S.
Unconsolidated, near-surface sediments can have a profound influence on the amplitudes and frequencies of ground shaking during earthquakes, and these effects should be accounted for when using amplitude observations for seismic hazard assessments. This study explores methods to use teleseismic arrivals recorded on linear receiver arrays to characterize widespread, shallow sedimentary...
Authors
Thomas L. Pratt
Santa Rosa's past and future earthquakes Santa Rosa's past and future earthquakes
Santa Rosa is no stranger to earthquakes. This northern California city was damaged several times in the late 19th and early 20th centuries by shaking from earthquakes, culminating in the devastating earthquake of 1906, whose rupture passed 20 miles to the west of the city on the San Andreas Fault. Then in 1969, Santa Rosa was again strongly shaken and buildings were damaged by a pair of...
Authors
Suzanne Hecker, Darcy K. McPhee, Victoria E. Langenheim, Janet T. Watt
High-frequency ground motion and source characteristics of the 2008 Wenchuan and 2013 Lushan, China, earthquakes High-frequency ground motion and source characteristics of the 2008 Wenchuan and 2013 Lushan, China, earthquakes
The 2008 MW7.9 Wenchuan and the 2013 MW6.6 Lushan earthquakes, which both occurred on the Longmen Shan thrust belt, show some interesting similarities and differences. Whereas the Wenchuan earthquake entailed a rupture zone that extended about 300 km northeastward, with fault slip extending to the surface, the Lushan earthquake was the result of a buried and much more compact zone of...
Authors
Lingyuan Meng, Yang Zang, Longquan Zhou
SKS splitting beneath Mount St. Helens: Constraints on subslab mantle entrainment SKS splitting beneath Mount St. Helens: Constraints on subslab mantle entrainment
Observations of seismic anisotropy can provide direct constraints on the character of mantle flow in subduction zones, critical for our broader understanding of subduction dynamics. Here we present over 750 new SKS splitting measurements in the vicinity of Mount St. Helens in the Cascadia subduction zone using a combination of stations from the iMUSH broadband array and Cascades Volcano
Authors
Caroline M Eakin, Erin A. Wirth, Abraham Wallace, Carl W Ulberg, Kenneth C Creager, Geoffrey A Abers
Rupture branching structure of the 2014 Mw 6.0 South Napa, California earthquake inferred from explosion-generated fault-zone trapped waves Rupture branching structure of the 2014 Mw 6.0 South Napa, California earthquake inferred from explosion-generated fault-zone trapped waves
We present evidence for multiple fault branches of the West Napa fault zone (WNFZ) based on fault‐zone trapped waves (FZTWs) generated by two explosions that were detonated within the main surface rupture zone produced by the 24 August 2014 Mw 6.0 South Napa earthquake. The FZTWs were recorded by a 15‐kilometer‐long dense (100 m spacing) linear seismic array consisting of 155 4.5‐hertz...
Authors
Yong-Gang Li, Rufus D. Catchings, Mark Goldman
Preliminary report on engineering and geological effects of the July 2019 Ridgecrest earthquake sequence Preliminary report on engineering and geological effects of the July 2019 Ridgecrest earthquake sequence
The Ridgecrest Earthquake sequence included a foreshock event on July 4 2019 (M6.4) and a M7.1 mainshock event on July 5 2019. These events occurred in the Eastern California Shear Zone, near Indian Wells Valley, south of China Lake and west of Searles Valley. GEER has partnered with several organizations to collect perishable data and document the important impacts of these events...
Authors
Scott J Brandenberg, Pengfei Wang, Chukwuebuka C Nweke, Kenneth Hudson, Silvia Mazzoni, Yousef Bozorgnia, Kenneth W. Hudnut, Craig A. Davis, Sean K Ahdi, Farzin Zareian, Jawad Fayaz, Richard D Koehler, Colin Chupik, Ian Pierce, Alana Williams, Sinan Akciz, Martin B Hudson, Tadahiro Kishida, Benjamin A. Brooks, Ryan D. Gold, Daniel J. Ponti, Katherine M. Scharer, Devin McPhillips, Christopher DuRoss, Todd Ericksen, Janis Hernandez, Jay Patton, Brian Olson, Timothy E. Dawson, Jerome Treiman, Kelly Blake, Jeffrey Buchhuber, Chris L M Madugo, Joseph Sun, Andrea Donnellan, Greg Lyzenga, Erik Conway
Depth determination of the 2010 El Mayor‐Cucapah earthquake sequence (M ≥ 4.0) Depth determination of the 2010 El Mayor‐Cucapah earthquake sequence (M ≥ 4.0)
The 2010 MW 7.2 El Mayor‐Cucapah earthquake ruptured a zone of ~120 km in length in northern Baja California. The geographic distribution of this earthquake sequence was well constrained by waveform relocation. The depth distribution, however, was poorly determined as it is near the edge of, or outside, the Southern California Seismic Network. Here we use two complementary methods to...
Authors
C. Yu, E. Hauksson, Z. Zhan, Elizabeth S. Cochran, D. Helmberger
Lithosphere and shallow asthenosphere rheology from observations of post-earthquake relaxation Lithosphere and shallow asthenosphere rheology from observations of post-earthquake relaxation
In tectonically active regions, post-earthquake motions are generally shaped by a combination of continued fault slippage (afterslip) on a timescale of days to months and viscoelastic relaxation of the lower crust and upper mantle on a timescale of days to years. Transient crustal motions have been observed following numerous magnitude >~7 earthquakes in various tectonic settings...
Authors
Frederick Pollitz