Publications

The first U.S. Tsunami Hazard Assessment (Dunbar and Weaver, 2008) was prepared at the request of the National Tsunami Hazard Mitigation Program (NTHMP). The NTHMP is a partnership formed between federal and state agencies to reduce the impact of tsunamis through hazard assessment, warning guidance, and mitigation. The assessment was conducted in response to a 2005 joint report by the...

Earthquake early warning (EEW) can reduce harm to people and infrastructure from earthquakes and tsunamis, but it has not been implemented in most high earthquake-risk regions because of prohibitive cost. Common consumer devices such as smartphones contain low-cost versions of the sensors used in EEW. Although less accurate than scientific-grade instruments, these sensors are globally...

Creation of an Enhanced Geothermal System relies on stimulation of fracture permeability through self-propping shear failure that creates a complex fracture network with high surface area for efficient heat transfer. In 2010, shear stimulation was carried out in well 27-15 at Desert Peak geothermal field, Nevada, by injecting cold water at pressure less than the minimum principal stress...

We describe observations of dynamic rupture events that spontaneously arise on meter-scale laboratory earthquake experiments. While low-frequency slip of the granite sample occurs in a relatively uniform and crack-like manner, instruments capable of detecting high frequency motions show that some parts of the fault slip abruptly (velocity >100 mm∙s-1, acceleration >20 km∙s-2) while the...

Tectonic tremor (TT) and low-frequency earthquakes (LFEs) have been found in the deeper crust of various tectonic environments globally in the last decade. The spatial-temporal behaviour of LFEs provides insight into deep fault zone processes. In this study, we examine recurrence times from a 12-yr catalogue of 88 LFE families with ∼730 000 LFEs in the vicinity of the Parkfield section...

We relocate 16 years of seismicity in the Coso Geothermal Field (CGF) using differential travel times and simultaneously invert for seismic velocities to improve our knowledge of the subsurface geologic and hydrologic structure. We expand on our previous results by doubling the number of relocated events from April 1996 through May 2012 using a new field-wide 3-D velocity model...

Recent modeling studies have explored whether earthquakes begin with a large aseismic nucleation process or initiate dynamically from the rapid growth of a smaller instability in a “cascade-up” process. To explore such a case in the laboratory, we study the initiation of dynamic rupture (stick slip) of a smooth saw-cut fault in a 76mm diameter cylindrical granite laboratory sample at 40...

Recent research indicates that the shallow mantle of the Cascadia subduction margin under near-coastal Pacific Northwest U.S. is cold and partially serpentinized, storing large quantities of water in this wedge-shaped region. Such a wedge probably formed to the south in California during an earlier period of subduction. We show by numerical modeling that after subduction ceased with the...

This paper summarizes the evaluation of ground motion simulation methods implemented on the SCEC Broadband Platform (BBP), version 14.3 (as of March 2014). A seven-member panel, the authorship of this article, was formed to evaluate those methods for the prediction of pseudo-­‐spectral accelerations (PSAs) of ground motion. The panel’s mandate was to evaluate the methods using tools...

The viability of carbon capture and storage (CCS) to reduce emissions of greenhouse gases depends on the ability to safely sequester large quantities of CO2 over geologic time scales. One concern with CCS is the potential of induced seismicity. We report on ongoing seismic monitoring by the U.S. Geological Survey (USGS) at a CCS demonstration site in Decatur, IL, in an effort to...

The Next Generation Attenuation‐West 2 (NGA‐West 2) 2014 ground‐motion prediction equations (GMPEs) model ground motions as a function of magnitude and distance, using empirically derived coefficients (e.g., Bozorgniaet al., 2014); as such, these GMPEs do not clearly employ earthquake source parameters beyond moment magnitude ( M) and focal mechanism. To better understand the magnitude...

The Maacama fault is the northward continuation of the Hayward–Rodgers Creek fault system and creeps at a rate of 5.7±0.1  mm/yr (averaged over the last 20 years) in Willits, California. Our paleoseismic studies at Haehl Creek suggest that the Maacama fault has produced infrequent large earthquakes in addition to creep. Fault terminations observed in several excavations provide evidence...