Publications
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Uncertainty in Vs30-based site response
Methods that account for site response range in complexity from simple linear categorical adjustment factors to sophisticated nonlinear constitutive models. Seismic‐hazard analysis usually relies on ground‐motion prediction equations (GMPEs); within this framework site response is modeled statistically with simplified site parameters that include the time‐averaged shear‐wave velocity to 30 m (VS30
Authors
Eric M. Thompson, David J. Wald
“Ductile to brittle” transition in thermally stable antigorite gouge at mantle pressures
General shear experiments on antigorite-rich serpentinite show a transition from ductile (distributed) to brittle (localized) deformation with increasing temperature from 300°C to 500°C at confining pressures from 1 to 2 GPa. The coefficient of friction associated with slip along fractures decreases from 0.23 to 0.07 with an increase in temperature from 300°C to 500°C. Velocity stepping experiment
Authors
Brooks P. Proctor, Greg Hirth
Afterslip behavior following the M6.0, 2014 South Napa earthquake with implications for afterslip forecasting on other seismogenic faults
The M6.0, 24 Aug. 2014 South Napa, California, earthquake exhibited unusually large slip for a California strike-slip event of its size with a maximum coseismic surface slip of 40-50 cm in the north section of the 15 km-long rupture. Although only minor (
Authors
James J. Lienkaemper, Stephen B. DeLong, Carolyn J Domrose, Carla M. Rosa
High-resolution seismic reflection imaging of growth folding and shallow faults beneath the Southern Puget Lowland, Washington State
Marine seismic reflection data from southern Puget Sound, Washington, were collected to investigate the nature of shallow structures associated with the Tacoma fault zone and the Olympia structure. Growth folding and probable Holocene surface deformation were imaged within the Tacoma fault zone beneath Case and Carr Inlets. Shallow faults near potential field anomalies associated with the Olympia
Authors
Jackson K. Odum, William J. Stephenson, Thomas L. Pratt, Richard J. Blakely
Potential improvements in horizontal very broadband seismic data in the IRIS/USGS component of the Global Seismic Network
The Streckeisen STS‐1 has been the primary vault‐type seismometer used in the over‐150‐station Global Seismographic Network (GSN). This sensor has long been known for its outstanding vertical, very long‐period (e.g., >100 s period), and low‐noise performance, although the horizontal long‐period noise performance is less well known. The STS‐1 is a limited, important resource, because it is no long
Authors
Adam T. Ringler, J.M. Steim, T Zandt, Charles R. Hutt, David C. Wilson, Tyler Storm
Lithospheric rheology constrained from twenty-five years of postseismic deformation following the 1989 Mw 6.9 Loma Prieta earthquake
The October 17, 1989 Mw 6.9 Loma Prieta earthquake provides the first opportunity of probing the crustal and upper mantle rheology in the San Francisco Bay Area since the 1906 Mw 7.9 San Francisco earthquake. Here we use geodetic observations including GPS and InSAR to characterize the Loma Prieta earthquake postseismic displacements from 1989 to 2013. Pre-earthquake deformation rates are constrai
Authors
Mong-Han Huang, Roland Burgmann, Fred Pollitz
Comparison of measurement- and proxy-based Vs30 values in California
This study was prompted by the recent availability of a significant amount of openly accessible measured VS30 values and the desire to investigate the trend of using proxy-based models to predict VS30 in the absence of measurements. Comparisons between measured and model-based values were performed. The measured data included 503 VS30 values collected from various projects for 482 seismographic st
Authors
Alan K. Yong
Effective stress, friction and deep crustal faulting
Studies of crustal faulting and rock friction invariably assume the effective normal stress that determines fault shear resistance during frictional sliding is the applied normal stress minus the pore pressure. Here we propose an expression for the effective stress coefficient αf at temperatures and stresses near the brittle-ductile transition (BDT) that depends on the percentage of solid-solid co
Authors
N.M. Beeler, Greg Hirth, Amanda M. Thomas, Roland Burgmann
Compilation of VS30 Data for the United States
VS30, the time-averaged shear-wave velocity (VS) to a depth of 30 meters, is a key index adopted by the earthquake engineering community to account for seismic site conditions. VS30 is typically based on geophysical measurements of VS derived from invasive and noninvasive techniques at sites of interest. Owing to cost considerations, as well as logistical and environmental concerns, VS30 data are
Authors
Alan Yong, Eric M. Thompson, David J. Wald, Keith L. Knudsen, Jack K. Odum, William J. Stephenson, Scott Haefner
Determining generic velocity and density models for crustal amplification calculations, with an update of the Boore and Joyner (1997) Generic Site Amplification for Graphic Site Amplification
This short note contains two contributions related to deriving depth‐dependent velocity and density models for use in computing generic crustal amplifications. The first contribution is a method for interpolating two velocity profiles to obtain a third profile with a time‐averaged velocity to depth Z that is equal to a specified value (e.g., for shear‐wave velocity VS, for Z=30 m, in which the
Authors
David Boore
Differential uplift and incision of the Yakima River terraces, central Washington State
The fault-related Yakima folds deform Miocene basalts and younger deposits of the Columbia Plateau in central Washington State. Geodesy implies ~2 mm/yr of NNE directed shortening across the folds, but until now the distribution and rates of Quaternary deformation among individual structures has been unclear. South of Ellensburg, Washington, the Yakima River cuts a ~600 m deep canyon across severa
Authors
Adrian M. Bender, Colin B. Amos, Paul R. Bierman, Dylan Rood, Lydia M. Staisch, Harvey M. Kelsey, Brian Sherrod
Evolution of fracture permeability of ultramafic rocks undergoing serpentinization at hydrothermal conditions: An experimental study
We performed flow-through laboratory experiments on five cylindrically cored samples of ultramafic rocks, in which we generated a well-mated through-going tensile fracture, to investigate evolution of fracture permeability during serpentinization. The samples were tested in a triaxial loading machine at a confining pressure of 50 MPa, pore pressure of 20 MPa, and temperature of 260°C, simulating a
Authors
Aida Farough, Diane E. Moore, David A. Lockner, R.P. Lowell