Publications

The square‐root‐impedance (SRI) method is a fast way of computing approximate site amplification that does not depend on the details from velocity models. The SRI method underestimates the peak response of models with large impedance contrasts near their base, but the amplifications for those models is often close to or equal to the root mean square of the theoretical full resonant (FR)...

The northern Nevada rift is a prominent mafic dike swarm and magnetic anomaly in north-central Nevada inferred to record the Middle Miocene (16.5-15.0 Ma) extension direction in the northern Basin and Range province in the western United States. From the 245°-250° rift direction, Basin and Range extension is inferred to have shifted 45° clockwise to a modern direction of 290°-300° during...

Significant earthquakes are increasingly occurring within the continental interior of the United States, including five of moment magnitude (Mw) ≥ 5.0 in 2011 alone. Concurrently, the volume of fluid injected into the subsurface related to the production of unconventional resources continues to rise. Here we identify the largest earthquake potentially related to injection, an Mw 5.7...

The Shoreline fault is a vertical strike‐slip fault running along the coastline near San Luis Obispo, California. Much is unknown about the Shoreline fault, including its slip rate and the details of its geometry. Here, I study the geometry of the Shoreline fault at seismogenic depth, as well as the adjacent section of the offshore Hosgri fault, using seismicity relocations and...

A 64-story, performance-based design building with reinforced concrete core shear walls and unique dynamic response modification features (tuned liquid sloshing dampers and buckling-restrained braces) has been instrumented with a monitoring array of 72 channels of accelerometers. The responses of the building to ambient motions from ground or wind were recorded and analyzed to identify...

Earthquakes trigger other earthquakes, but the physical mechanism of the triggering is currently debated. Most studies of earthquake triggering rely on earthquakes listed in catalogs, which are known to be incomplete around the origin times of large earthquakes and therefore missing potentially triggered events. Here we apply a waveform matched-filter technique to systematically detect...

We use LiDAR imagery to identify two fault scarps on latest Pleistocene glacial outwash deposits along the North Fork Nooksack River in Whatcom County, Washington (United States). Mapping and paleoseismic investigation of these previously unknown scarps provide constraints on the earthquake history and seismic hazard in the northern Puget Lowland. The Kendall scarp lies along the mapped...

Families of recurring low-frequency earthquakes (LFEs) within nonvolcanic tremor (NVT) on the San Andreas fault in central California show strong sensitivity to shear stress induced by the daily tidal cycle. LFEs occur at all levels of the tidal shear stress and are in phase with the very small, ~400 Pa, stress amplitude. To quantitatively explain the correlation, we use a model from the...

We employ a domain decomposition approach with Lagrange multipliers to implement fault slip in a finite-element code, PyLith, for use in both quasi-static and dynamic crustal deformation applications. This integrated approach to solving both quasi-static and dynamic simulations leverages common finite-element data structures and implementations of various boundary conditions...

The town of Mineral, Virginia (Va.), underwent an M=5.8 earthquake on August 23, 2011. A U.S. Geological Survey team was sent to visually inspect and document the damage in the cities of Richmond, Charlottesville, Louisa, and Mineral, Va. Our inspection concluded that the Modified Mercalli Intensity rating of moderate (V) to very strong (VII) is consistent with the expected and observed...

The University of Nevada Las Vegas’ (UNLV) Science and Engineering Building is at the cutting edge of environmentally friendly design. As the result of a recent effort by the U.S. Geological Survey’s National Strong Motion Project in cooperation with UNLV, the building is now also in the forefront of buildings installed with structural monitoring systems to measure response during...

The mainshock and moderate‐magnitude aftershocks of the 6 April 2009 M 6.3 L’Aquila seismic sequence, about 90 km northeast of Rome, provided the first earthquake ground‐motion recordings in the urban area of Rome. Before those recordings were obtained, the assessments of the seismic hazard in Rome were based on intensity observations and theoretical considerations. The L’Aquila...