Publications
Filter Total Items: 1857
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 deposits, in
Authors
Thomas L. Pratt
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 nearby, m
Authors
Suzanne Hecker, Darcy K. McPhee, Victoria E. Langenheim, Janet T. Watt
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 Observator
Authors
Caroline M Eakin, Erin A. Wirth, Abraham Wallace, Carl W Ulberg, Kenneth C Creager, Geoffrey A Abers
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, including the
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 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)
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 constrain the
Authors
C. Yu, E. Hauksson, Z. Zhan, Elizabeth S. Cochran, D. Helmberger
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: continental rift
Authors
Fred Pollitz
Petrologic and mineral physics database for use with the U.S. Geological Survey National Crustal Model
We present a petrologic and mineral physics database as part of the U.S. Geological Survey National Crustal Model (NCM). Each of 209 geologic units, 134 of which are currently part of the geologic framework within the NCM, was assigned a mineralogical composition according to generalized classifications with some refinement for specific geologic formations. This report is concerned with the petrol
Authors
Theron Sowers, Oliver S. Boyd
Satellite observations of surface deformation at the Coso Geothermal Field, California
Surface deformation time series and rates are identified at the Coso Geothermal Field (CGF) and surrounding areas by applying interferometric synthetic aperture radar (InSAR) to satellite scenes from Envisat (June 2004 ̶ October 2010) and Sentinel (November 2014 – April 2018). The measurements are done in the line of sight (LOS) to each satellite, within an area of size ~450 km2, at the location
Authors
Mariana Eneva, Andrew Barbour, David Adams, Vicky Hsiao, Kelly Blake, Giacomo Falorni, Roberto Locatelli
Landscape change associated with the upper Scenic Drive landslide, La Honda, California, January 10–June 28, 2017
La Honda, California, is a small town in unincorporated San Mateo County, located on the west edge of the San Francisco Peninsula in the Santa Cruz Mountains, between San Francisco and San Jose. The Scenic Drive area of La Honda has experienced several past episodes of landslide motion, which were documented in 1998, 2005, and 2006. This report documents the movement of the upper Scenic Drive land
Authors
Alexandra J. Pickering, Carol S. Prentice, Stephen B. DeLong
Variability in synthetic earthquake ground motions caused by source variability and errors in wave propagation models
Numerical simulations of earthquake ground motions are used both to anticipate the effects of hypothetical earthquakes by forward simulation and to infer the behaviour of the real earthquake source ruptures by the inversion of recorded ground motions. In either application it is necessary to assume some Earth structure that is necessarily inaccurate and to use a computational method that is also i
Authors
Paul A. Spudich, Antonella Cirella, Laura Scognamiglio, Elisa Tinti
Determining Moho depth beneath sedimentary basins using regional Pn multiples
The study of the Moho beneath thick sedimentary basins involving natural earthquakes is challenging, as low‐velocity materials often cause strong reverberations that mask Moho signals. Here, we develop a method to determine the depth of the Moho by taking advantage of the presence of the sediments. The method utilizes the first Pn crustal multiple from regional earthquakes PnPn and its differentia
Authors
C. Yu, Z. Zhan, E. Hauksson, Elizabeth S. Cochran, D. Helmberger
Event detection performance of the PLUM earthquake early warning algorithm in southern California
We test the Japanese ground‐motion‐based earthquake early warning (EEW) algorithm, propagation of local undamped motion (PLUM), in southern California with application to the U.S. ShakeAlert system. In late 2018, ShakeAlert began limited public alerting in Los Angeles to areas of expected modified Mercalli intensity (IMMI) 4.0+ for magnitude 5.0+ earthquakes. Most EEW systems, including ShakeAle
Authors
Elizabeth S. Cochran, Julian Bunn, Sarah E. Minson, Annemarie S. Baltay, Deborah L. Kilb, Y. Kodera, Mitsuyuki Hoshiba