Publications

Geodetic velocity data provide first-order constraints on crustal surface strain rates, which in turn are linked to seismic hazard. Estimating the 2-D surface strain tensor everywhere requires knowledge of the surface velocity field everywhere, while geodetic data such as Global Navigation Satellite System (GNSS) only have spatially scattered measurements on the surface of the Earth. To use these

Most conventional approaches for assessing liquefaction triggering hazards generally rely on simplified procedures that involve identifying liquefaction susceptible layers and calculating a factor of safety against liquefaction (FSL) in each layer. Such procedures utilize deterministic semi-empirical models for standard penetration test (SPT), cone penetrometer test (CPT), or shear wave velocity (

The large graben-like troughs and smooth plains visible on the surface of Ariel are indicative of a period of high heat flow in the Uranian moon's past. High heat flows on icy moons like Ariel can also enable viscous flow that removes impact crater topography, a process called viscous relaxation. Here we use numerical modeling to investigate the conditions necessary to viscously relax Ariel's larg

The initial effects from an asteroid impact are generally well characterized and include thermal radiation and blast waves. If the impactor is sufficiently large, either an earthquake or tsunami can also result, depending on whether the impact occurs over land or water. However, the longer-term effects that extend beyond the area initially affected are less well characterized. Because regional ef

We present new X-ray fluorescence compositions of 27 core samples from Phase 3, Hole G of the San Andreas Fault Observatory at Depth, nearly doubling the published dataset for the core. The new analyses consist of major and trace element compositions and the first published data for rare earth elements from Hole G. Whole-rock compositions were obtained to further the analysis of active geochemical

Fault displacement models (FDMs) are an essential component of the probabilistic fault displacement hazard analyses (PFDHA), much like ground motion models in the probabilistic seismic hazard analyses for ground motion hazards. In this study, we develop several principal surface FDMs for strike-slip earthquakes. The model development is based on analyses of the new and comprehensive fault displac

The rate of fault zone restrengthening between earthquakes can be influenced by both frictional and cohesive healing processes. Friction is dependent on effective normal stress while cohesion is independent of normal stress, potentially explaining—in part—the lack of depth dependence of earthquake stress drops. Although amenable to laboratory testing, few studies have systematically addressed the

Sea level rise is expected to affect coastal areas all around the world, including the estuarine environment. New bathymetry collected in 2014 provided a unique opportunity to test the modeling of Elmilady et al. (2019), who presented a morphodynamic DELFT3D model of San Pablo Bay, California, that included detailed tidal water movement, wind-wave action, sediment transport, and resulting bed leve

Debris flows are a type of mass movement that is more likely after wildfires, and while existing hazard assessments evaluate the rainfall intensities that are likely to trigger debris flows, no operational hazard assessment exists for identifying the areas where they will run out after initiation. Fifteen participants who work in a wide range of job functions associated with southern California po

Dynamic earthquake rupture simulations are used to understand earthquake mechanics and the ground shaking that earthquakes produce. These simulations can help diagnose past earthquake behavior and are also used to generate scenarios of possible future earthquakes. Traditional dynamic rupture models generally assume elastic rock response, but this can lead to peak on‐fault slip rates and ground sha

One of the key factors in obtaining precise and accurate 230Th ages of corals, especially for corals with ages less than a few thousand years, is the correction for non-radiogenic 230Th based on an initial 230Th/232Th value (230Th/232Th0). Studies that consider coral 230Th/232Th0 values in intertidal environments are limited, and it is in these environments that corals have Th concentrations 100–1

Near-Earth Objects (NEOs) are asteroids and comets that orbit the Sun, but have orbits that can bring them into Earth’s neighborhood—within 30 million miles of Earth’s orbit. Planetary defense is “applied planetary science” to address the NEO impact risks on Earth. This National Preparedness Strategy and Action Plan for Near-Earth Objects and Planetary Defense (2023 Planetary Defense Strategy) upd