Publications

To understand and predict the behaviors of strong ground motions incurred during devastating earthquakes, studies focused on the “effects of surface geology (ESG) on seismic motions” (following tradition, herein contracted as: “ESG”) have progressed steadily in the last three decades. These ESG studies typically involve in situ measurements of the wavefield and commonly apply both...

Subsurface wastewater injection has increased the seismicity rate within the Raton Basin over more than two decades, with the basin-wide injection rate peaked between 2009-2015. To understand the evolution of injection-induced earthquakes, we systematically analyzed 2016-2024 broadband recordings with a machine-learning-based phase picker and constructed a catalog with 95,993 earthquakes...

The Concord fault constitutes a major branch of the Pacific–North America transform plate boundary in Northern California, bridging the strike‐slip Bartlett Springs ‐ Green Valley Fault system to the north with the Greenville and Calaveras Faults to the south. Like many faults in the San Francisco Bay Area its long‐term slip is partially accommodated by aseismic slip (creep). Although...

Rare Earth Elements (REEs) are increasingly attracting attention globally due to their pivotal role in enhancing the performance of various hightech devices. Small amounts of these elements greatly improve the performance of materials, making magnets stronger, lenses clearer, lights brighter, batteries last longer, etc. Here we examine the notion that REEs from the Moon might compete...

Dynamic earthquake triggering is commonly identified through the temporal correlation between increased seismicity rates and global earthquakes that are possible triggering events. However, correlation does not imply causation. False positives may occur when unrelated seismicity rate changes coincidently occur at around the time of candidate triggers. We investigate the expected false...

We report on six Findings related to the benefit of Artemis Base Camp (ABC) to lunar geoscience (Figure 1). These Findings are on the topics of 1) Repeat field site visits; 2) Geological experiments; 3) Satellite ABC campus(es); 4) Advanced lab equipment; 5) Frequent and resource-intensive EVAs; and 6) Geoscience STEM engagement. Lastly, we consider certain issues and caveats meriting...

Earth’s surface is sculpted by numerous processes that move sediment, ranging from gradual and benign to abrupt and catastrophic. Although infrequent, high-magnitude sediment mobilization events can be hazardous to people and infrastructure, leaving topographic imprints on the landscape and remarkable narratives in the historical record. Hazardous events such as fires, storms, and...

We examine the relationship between peak ground velocity (PGV) and cumulative absolute displacement (CAD) for 49 Mw 3 – 6 earthquakes in the San Francisco Bay Area (SFBA) and gain insight into the spatiotemporal partitioning of seismic energy in ground motion records with respect to source, path, and site effects. PGV and CAD are positively correlated, but there can be large deviations...

A high-resolution seismic velocity model for both P and S waves is essential for the San Francisco Bay (SFB) region to accurately simulate earthquake ground motions and assess seismic hazards in this high-risk region. We present new three-dimensional P-wave and S-wave velocity (Vp and Vs) models of the SFB region developed using joint tomographic inversion with a rich set of earthquake...

The way seismicity responds to periodic stress perturbations offers crucial insights into the processes that can trigger an earthquake. Laboratory and theoretical analyses have shown that the period of imposed forcing and source properties affect the sensitivity to triggering, but frequency-dependent triggering of tectonic faults is poorly understood. The rate of low-frequency...

CO2 sequestration in deep saline formations is an effective and important process to control the rapid rise in CO2 emissions. The process of injecting CO2 requires reliable predictions of the stress in the formation and the fluid pressure distributions – particularly since monitoring of the CO2 migration is difficult – to mitigate leakage, prevent induced seismicity, and analyze wellbore...

The moons Europa and Enceladus both have water-ice dominated shells tens of kilometers thick overlying global oceans. Both moons are tidally heated and have a high rock mass fractions relative to other moons in their system, and both have youthful, tectonically deformed surfaces. Despite their many commonalities, the surfaces of the two moons bear little resemblance to one another...