Publications

The focal mechanisms of earthquakes in Southern California before and after four M ≥ 6.7 main shocks provide insight into how fault systems respond to stress and changes in stress. The main shock static stress changes have two observed impacts on the seismicity: changing the focal mechanisms in a given location to favor those aligned with the static stress change and changing the spatial distribut

The midband sensitivity of a seismic instrument is one of the fundamental parameters used in published station metadata. Any errors in this value can compromise amplitude estimates in otherwise high-quality data. To estimate an upper bound in the uncertainty of the midband sensitivity for modern broadband instruments, we compare daily microseism (4- to 8-s period) amplitude ratios between the vert

Creep in the San Andreas Fault Observatory at Depth (SAFOD) drillhole is localized to two foliated gouges, the central deforming zone (CDZ) and southwest deforming zone (SDZ). The gouges consist of porphyroclasts of serpentinite and sedimentary rock dispersed in a foliated matrix of Mg-smectite clays that formed as a result of shearing-enhanced reactions between the serpentinite and quartzofeldspa

Surface creep rate, observed along five branches of the dextral San Andreas fault system in northern California, varies considerably from one section to the next, indicating that so too may the depth at which the faults are locked. We model locking on 29 fault sections using each section’s mean long‐term creep rate and the consensus values of fault width and geologic slip rate. Surface creep rate

The September 2013 Mw7.7 Balochistan earthquake ruptured a ∼200-km-long segment of the curved Hoshab fault in southern Pakistan with 10±0.2 m of peak sinistral and ∼1.7±0.8 m of dip slip. This rupture is unusual because the fault dips 60±15° towards the focus of a small circle centered in northwest Pakistan, and, despite a 30° increase in obliquity along strike, the ratios of strike and dip slip r

Structure from Motion (SfM) generates high-resolution topography and coregistered texture (color) from an unstructured set of overlapping photographs taken from varying viewpoints, overcoming many of the cost, time, and logistical limitations of Light Detection and Ranging (LiDAR) and other topographic surveying methods. This paper provides the first investigation of SfM as a tool for mapping faul

We consider whether mm-scale earthquake-like seismic events generated in laboratory experiments are consistent with our understanding of the physics of larger earthquakes. This work focuses on a population of 48 very small shocks that are foreshocks and aftershocks of stick–slip events occurring on a 2.0 m by 0.4 m simulated strike-slip fault cut through a large granite sample. Unlike the larger s

In this study I consider the ground motions generated by 11 moderate (Mw4.0-5.6) earthquakes in the central and eastern United States that are thought or suspected to be induced by fluid injection. Using spatially rich intensity data from the USGS “Did You Feel It?” system, I show that the distance decay of intensities for all events is consistent with that observed for tectonic earthquakes in th

The Raton Basin of southern Colorado and northern New Mexico is an actively produced hydrocarbon basin that has experienced increased seismicity since 2001, including the August 2011 Mw5.3 Trinidad normal faulting event. Following the 2011 earthquake, regional seismic observations were used to relocate 21 events, including the 2011 main shock, two foreshocks, and 13 aftershocks. Additionally, inte

The tectonics of the Pacific margin of North America between Vancouver Island and south-central Alaska are dominated by the northwest motion of the Pacific plate with respect to the North America plate at a velocity of approximately 50 mm/yr. In the south of this mapped region, convergence between the northern extent of the Juan de Fuca plate (also known as the Explorer microplate) and North Ameri

Current studies have demonstrated a sharp increase in human losses due to earthquakes. These alarming levels of casualties suggest the need for large-scale investment in seismic risk mitigation, which, in turn, requires an adequate understanding of the extent of the losses, and location of the most affected regions. Recent developments in global and uniform datasets such as instrumental and histor

We investigate the ongoing seismicity in the Raton Basin and find that the deep injection of wastewater from the coal‐bed methane field is responsible for inducing the majority of the seismicity since 2001. Many lines of evidence indicate that this earthquake sequence was induced by wastewater injection. First, there was a marked increase in seismicity shortly after major fluid injection began in