Publications

The M5.8 23 August 2011 Mineral, Virginia, earthquake was felt over nearly the entire eastern United States and was recorded by a wide array of seismic broadband instruments. The earthquake occurred ~200 km southeast of the boundary between two distinct geologic belts, the Piedmont and Blue Ridge terranes to the southeast and the Valley and Ridge Province to the northwest. At a dominant...

This year marks the sesquicentennial anniversary of the end of the American Civil War, a conflict that Abraham Lincoln called a “mighty scourge.” It was one of the most poignant periods in U.S. history, laying bare political, economic, social, and moral divergence between Northern and Southern states. The cause of the divergence that led to war was slavery [e.g., McPherson, 1988, chap. 3...

Introduction A number of different government-funded seismic data centers offer free open-access data (e.g., U.S. Geological Survey, National Earthquake Information Center, the Incorporated Research Institutions for Seismology (IRIS), and Data Management System), which can be freely downloaded and shared among different members of the community (Lay, 2009). To efficiently share data, it...

Scaling plays a crucial role in designing experiments aimed at understanding the behavior of landslides, debris flows, and other geomorphic phenomena involving grain-fluid mixtures. Scaling can be addressed by using dimensional analysis or – more rigorously – by normalizing differential equations that describe the evolving dynamics of the system. Both of these approaches show that...

Groundwater levels were offset in bedrock observation wells, measured by the U.S. Geological Survey or others, as far as 553 km from the Mw 5.8 Mineral, Virginia (USA), earthquake on 23 August 2011. Water levels dropped as much as 0.47 m in 34 wells and rose as much as 0.15 m in 12 others. In some wells, which are as much as 213 m deep, the water levels recovered from these deviations in...

We present new marine seismic‐reflection profiles and bathymetric maps to characterize Holocene depositional patterns, submarine landslides, and active faults beneath eastern and central Prince William Sound (PWS), Alaska, which is the eastern rupture patch of the 1964 Mw 9.2 earthquake. We show evidence that submarine landslides, many of which are likely earthquake triggered, repeatedly...

Subduction zone megathrust faults produce most of the world’s largest earthquakes. Although the physical properties of these faults are difficult to observe directly, their frictional strength can be estimated indirectly by constraining the orientations of the stresses that act on them. A global investigation of stress orientations in subduction zones finds that the maximum compressive...

Detailed geodetic imaging of earthquake rupture enhances our understanding of earthquake physics and induced ground shaking. The April 25, 2015 Mw 7.8 Gorkha, Nepal earthquake is the first example of a large continental megathrust rupture beneath a high-rate (5 Hz) GPS network. We use GPS and InSAR data to model the earthquake rupture as a slip pulse of ~20 km width, ~6 s duration, and...

The Mediterranean region is seismically active due to the convergence of the Africa Plate with the Eurasia plate. Present day Africa-Eurasia motion ranges from ~4 millimeters per year (mm/yr) in a northwest-southeast direction in the western Mediterranean to ~10 mm/yr (north-south) in the eastern Mediterranean. The Africa-Eurasia plate boundary is complex, and includes extensional and...

Three broadband simulation methods are used to generate synthetic ground motions for the 2011 Mineral, Virginia, earthquake and compare with observed motions. The methods include a physics‐based model by Hartzell et al. (1999, 2005), a stochastic source‐based model by Boore (2009), and a stochastic site‐based model by Rezaeian and Der Kiureghian (2010, 2012). The ground‐motion dataset...

Mount St. Helens began erupting in late 2004 following an 18 year quiescence. Swarms of repeating earthquakes accompanied the extrusion of a mostly solid dacite dome over the next 4 years. In some cases the waveforms from these earthquakes evolved slowly, likely reflecting changes in the properties of the volcano that affect seismic wave propagation. We use coda-wave interferometry to...

The Frazier Mountain paleoseismic site is located within the northern Big Bend of the southern San Andreas Fault (lat 34.8122° N., lon 118.9034° W.), in a small structural basin formed by the fault (fig. 1). The site has been the focus of over a decade of paleoseismic study due to high stratigraphic resolution and abundant dateable material. Trench 1 (T1) was initially excavated as a 50...