Publications

The limits of detection for earthquake surface deformation in the spatial domain have improved with advances in remote sensing imagery data availability, resolution, and analysis. Sub-pixel correlation and digital elevation model (DEM) differencing from sub-meter, earthquake-spanning satellite optical imagery has enhanced surface rupture mapping and deformation measurements. However...

We use >4500 measurements of crustal structure to investigate the seismic structure of continental crust, Archean to Mesozoic–Cenozoic. The mean crustal thickness of continents, including their margins, is 36.5 km. We find that Archean, Paleoproterozoic, and Mesoproterozoic crust have similar mean crustal thickness (41 km), seismic velocities, Vp/Vs ratio, and density. Crusts of these...

Estimates of coseismic vertical displacements from past and potential future subduction zone earthquakes provide critical constraints on regional seismic and tsunami hazard. Many studies use elastic homogeneous half-space models to calculate vertical displacements from a specified earthquake slip distribution, neglecting complexities of 3D structure in subduction zone settings. Here, we...

Mercury hosts widespread smooth plains that are concentrated in the Caloris impact basin, in an annulus surrounding the Caloris basin, and in the adjacent northern smooth plains. The origins of these smooth plains are uncertain, although prior work suggests these plains in the northwestern Caloris annulus might reflect volcanic activity, impact ejecta, or a combination of the two...

The 2011 Mw9.1 Tohoku-oki earthquake is exceptional among great earthquakes for having peak slip of ~50-70 m on the shallowest portion of the plate boundary megathrust. International Ocean Discovery Program Expedition 405 drilled multiple holes through the megathrust in the large slip region and at a Pacific Plate input site. The megathrust preferentially develops at the top or base of...

Gridded (or background) seismicity models are a critical component of probabilistic seismic hazard assessments, accounting for off‐fault and smaller‐magnitude earthquakes. They are typically developed by declustering and spatially smoothing an earthquake catalog to estimate a long‐term seismicity rate that can be used to forecast future earthquakes. Here, we present new gridded...

We simulate ground shaking in western Washington State from hypothetical Mw7.0–7.5 earthquakes on the southern Whidbey Island fault (SWIF). Ground motions are modeled considering kinematic source distributions on a complex fault plane, a 3D seismic velocity model, and region‐specific soil velocity models. We run simulations with varying model resolutions, including regional‐scale...

Many subsurface processes involve transitions in granular material states, from arrested to creeping to flowing. Experiments and frameworks for idealized systems reveal that granular fabrics develop during shearing, co-evolve with applied stress, and govern such transitions. We use microtomography to test whether fabrics at two San Andreas fault sites reflect slip history and whether...

Deep long-period (DLP) earthquakes have been observed at many volcanic settings around the world and linked to the magmatic processes that drive volcanic unrest. At the Lassen Volcanic Center (LVC) of the Cascade arc, limited detection of DLP activity hinders classification of anomalous seismic behavior and its relationship to the LVC magmatic system. This study uses a template matching...

We describe a newly developed method for recovering high-resolution images of seismic discontinuities, such as subducting slabs, in 3D. Our method makes use of converted S →P or P →S waves observed by dense arrays of seismometers to infer the locations and relative strengths of seismic discontinuities at depth in a target region. Observed direct and converted waves are backpropagated to...

Based on observation and data from meteorites and in situ scientific missions, experiments as well as models, the Martian mantle is assumed to share some compositional and mineralogical affinity with the terrestrial mantle. However, there might be subtle differences like the Martian mantle being more ferroan. Yet, we do not have any direct analysis of a Martian mantle rock to confirm...

Geothermal energy is a clean and renewable resource that depends on the ability to move water through hot rock. In many locations, the ability to move water through rock requires the presence of extensive natural or human-made systems of fractures. However, these fracture systems are influenced by a variety of complex processes that occur at the temperature and pressure conditions found...