Publications

This study is to determine the detailed response of shear strength and other fault properties to changes in normal stress at room temperature using dry initially bare rock surfaces of granite at normal stresses between 5 and 7 MPa. Rapid normal stress changes result in gradual, approximately exponential changes in shear resistance with fault slip. The characteristic length of the...

The 2016 Kumamoto, Japan, earthquake sequence, culminating in the Mw=7.0 16 April 2016 main shock, occurred within an active tectonic belt of central Kyushu. GPS data from GEONET reveal transient crustal motions from several millimeters per year up to ∼3 cm/yr during the first 8.5 months following the sequence. The spatial pattern of horizontal postseismic motions is shaped by both...

On 16 September 2015, a Mw 8.3 earthquake ruptured the subduction zone offshore of Illapel, Chile, generating an aftershock sequence with 14 Mw 6.0–7.0 events. A double source W phase moment tensor inversion consists of a Mw 7.2 subevent and the main Mw 8.2 phase. We determine two slip models for the mainshock, one using teleseismic broadband waveforms and the other using static GPS and...

A variety of physical mechanisms are thought to be responsible for the triggering and spatiotemporal evolution of aftershocks. Here we analyze a vigorous aftershock sequence and postseismic geodetic strain that occurred in the Yuha Desert following the 2010 Mw 7.2 El Mayor-Cucapah earthquake. About 155,000 detected aftershocks occurred in a network of orthogonal faults and exhibit...

Probabilistic forecasting of earthquake‐producing fault ruptures informs all major decisions aimed at reducing seismic risk and improving earthquake resilience. Earthquake forecasting models rely on two scales of hazard evolution: long‐term (decades to centuries) probabilities of fault rupture, constrained by stress renewal statistics, and short‐term (hours to years) probabilities of...

We determine Modified Mercalli (Seismic) Intensities (MMI) for nine onshore earthquakes of magnitude 4.5 and larger that occurred in central and western Washington between 1989 and 1999, on the basis of effects reported in postal questionnaires, the press, and professional collaborators. The earthquakes studied include four earthquakes of M5 and larger: the M5.0 Deming earthquake of...

The ultimate goal of earthquake early warning (EEW) is to provide local shaking information to users before the strong shaking from an earthquake reaches their location. This is accomplished by operating one or more real‐time analyses that attempt to predict shaking intensity, often by estimating the earthquake’s location and magnitude and then predicting the ground motion from that...

We analyze the recorded responses of a 64-story, instrumented, concrete core shear wall building in San Francisco, California, equipped with tuned sloshing liquid dampers (TSDs) and buckling restraining braces (BRBs). Previously, only ambient data from the 72-channel array in the building were studied (Çelebi et al. 2013). Recently, the 24 August 2014 Mw 6.0 Napa and three other...

This year, the National Earthquake Hazards Reduction Program (NEHRP) turns 40, four decades since the Earthquake Hazards Reduction Act of 1977 was enacted establishing the Program, spurring numerous federal, state, and community actions to reduce earthquake losses in the U.S.A. and its territories and setting a standard for earthquake loss‐reduction projects internationally. Four...

Deep sedimentary basins are known to increase the intensity of ground motions, but this effect is implicitly considered in seismic hazard maps used in U.S. building codes. The basin amplification of ground motions from subduction earthquakes is particularly important in the Pacific Northwest, where the hazard at long periods is dominated by such earthquakes. This paper evaluates the...

Residuals between ground‐motion data and ground‐motion prediction equations (GMPEs) can be decomposed into terms representing earthquake source, path, and site effects. These terms can be cast in terms of repeatable (epistemic) residuals and the random (aleatory) components. Identifying the repeatable residuals leads to a GMPE with reduced uncertainty for a specific source, site, or path...

Tectonic stress in the crust evolves during a seismic cycle, with slow stress accumulation over interseismic periods, episodic stress steps at the time of earthquakes, and transient stress readjustment during a postseismic period that may last months to years. Static stress transfer to surrounding faults has been well documented to alter regional seismicity rates over both short and long...