Publications

The Sierra Madre fault system accommodates contraction within a large restraining bend area of the San Andreas fault along the northern margin of the Los Angeles metropolitan area in Southern California. Reverse slip along this fault system during earthquakes controls growth of the San Gabriel Mountains and poses a significant seismic hazard to the region. Here, we measure the late...

We employ strong motion seismograms and static offsets from the Global Positioning System, Interferometric Synthetic Aperture Radar, and other measurements in order to derive a coseismic slip and afterslip model of the M6.0 24 August 2014 South Napa earthquake. This earthquake ruptured an ∼13‐km‐long portion of the West Napa fault with predominantly right‐lateral strike slip. In the...

The behavior of the suspension bridge in Carquinez, CA, during the Mw6.0 24 August 2014 South Napa, CA earthquake is studied. Utilizing data from an extensive array of accelerometers that recorded the earthquake-excited motions, dynamic characteristics such as modes, corresponding frequencies and damping are identified and compared with previous studies that used ambient data of the deck...

The U.S. Geological Survey (USGS), created in 1879, is the national geological survey for the United States and the sole science agency within its cabinet-level bureau, the Department of the Interior. The USGS has a broad mission, including: serving the Nation by providing reliable scientific information to describe and understand the Earth; minimize loss of life and property from...

Seismic hazard associated with Cascadia megathrust earthquakes is strongly dependent on the landward rupture extent and heterogeneous fault properties. We use 3-D numerical simulations and a seismic velocity model for Cascadia to estimate coseismic deformation due to ~M9 earthquake scenarios. Our earthquake source model is based on observations of the 2010 M8.8 Maule and 2011 M9.0 Tohoku

We compared near-fault velocity spectra recorded during laboratory experiments to that of natural earthquakes. We fractured crystalline rock samples at room temperature and intermediate confining pressure (50 MPa). Subsequent slip events were generated on the fracture surfaces under higher confinement (300 MPa). Velocity spectra from rock fracture resemble the inverse frequency (1/f)...

Investigation of ground failure triggered by the 2018 MwMw 7.1 Anchorage earthquake showed that landslides, liquefaction, and ground cracking all occurred and caused significant damage. Shallow rock falls and rock slides were the most abundant types of landslides, but they occurred in smaller numbers than global models that are based on earthquake magnitude predict; this might result...

We investigated the potential role of ballast sediment from coastal and transoceanic oil tankers arriving and de-ballasting in Port Valdez as a vector for the introduction of invasive benthic foraminifera in Prince William Sound, Alaska. Forty-one ballast sediment samples were obtained in 1998-1999 from 11 oil tankers that routinely discharged their ballast in Prince William Sound after...

Linking fault behavior over many earthquake cycles to individual earthquake behavior is a primary goal in tectonic geomorphology, particularly across an entire plate boundary. Here, we examine the 1150-km-long, right-lateral Queen Charlotte-Fairweather fault system using comprehensive multibeam bathymetry data acquired along the Queen Charlotte Fault (QCF) offshore southeastern Alaska...

This is a cursory study of the recorded responses of three buildings instrumented by the U.S. Geological Survey (USGS) in Anchorage, Alaska, during the MwMw 7.1 earthquake of 30 November 2018. The earthquake caused the strongest shaking in Anchorage since the well‐known 1964 MwMw 9.2 Great Alaska earthquake. Since the 1964 event, several structures (buildings and bridges) in Anchorage...

Station noise levels play a fundamental limitation in our ability to detect seismic signals. These noise levels are frequency-dependent and arise from a number of physically different drivers. At periods greater than 100 s, station noise levels are often limited by the self-noise of the instrument as well as the sensitivity of the instrument to non-seismic noise sources. Recently...

Debris flows represent one of the most dangerous types of mass movements, because of their high velocities, large impact forces and long runout distances. This review describes the available debris-flow monitoring techniques and proposes recommendations to inform the design of future monitoring and warning/alarm systems. The selection and application of these techniques is highly...