Publications

We examine the hypothesis that dynamic deformations associated with seismic waves trigger earthquakes in many tectonic environments. Our analysis focuses on seismicity at close range (within the aftershock zone), complementing published studies of long-range triggering. Our results suggest that dynamic triggering is not confined to remote distances or to geothermal and volcanic regions...

The origin and evolution of cratonic roots has been debated for many years. Precambrian cratons are underlain by cold lithospheric roots that are chemically depleted. Thermal and petrologic data indicate that Archean roots are colder and more chemically depleted than Proterozoic roots. This observation has led to the hypothesis that the degree of depletion in a lithospheric root depends...

[1] We present a new crustal section across northwest China based on a seismic refraction profile and geologic mapping. The 1100‐km‐long section crosses the southern margin of the Chinese Altai Mountains, Junggar Accretional Belt and eastern Junggar basin, easternmost Tianshan Mountains, and easternmost Tarim basin. The crustal velocity structure and Poisson's ratio (σ), which provide a...

Using P and S arrival times from 4625 local and regional earthquakes recorded at 174 seismic stations and associated geophysical investigations, this paper presents a three‐dimensional crustal and upper mantle velocity structure of southwestern China (21°–34°N, 97°–105°E). Southwestern China lies in the transition zone between the uplifted Tibetan plateau to the west and the Yangtze...

This report describes seismic data obtained during the fourth Seismic Hazard Investigation of Puget Sound (SHIPS) experiment, termed Seattle SHIPS . The experiment was designed to study the influence of the Seattle sedimentary basin on ground shaking during earthquakes. To accomplish this, we deployed seismometers over the basin to record local earthquakes, quarry blasts, and teleseisms...

Two-dimensional convection models with moving continents show that continents profoundly affect the pattern of mantle convection. If the continents are wider than the wavelength of the convection cells (-3000 km, the thickness of the mantle), they cause neighboring deep mantle thermal upwellings to coalesce into a single focused upwelling. This focused upwelling zone will have a...

This report was prepared in response to a written request from the City of Vallejo, California, to the U.S. Geological Survey (USGS). By letter of October 4, 2002, the City requested that the USGS "provide advice to the City’s LNG Health and Safety Committee on its review of a potential liquid natural gas project" on the southern portion of Mare Island. The City specifically requested...

No abstract available.

The Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, the Geophysical Institute of the University of Alaska Fairbanks, and the Alaska Division of Geological and Geophysical Surveys, has maintained seismic monitoring networks at potentially active volcanoes in Alaska since 1988 (Power and others, 1993; Jolly and others, 1996; Jolly and others, 2001)...

The San Andreas fault is the longest fault in California and one of the longest strikeslip faults in the world, yet little is known about the aftershocks following the most recent great event on the San Andreas, the M 7.8 San Francisco earthquake, on 18 April 1906. This open-file report is a compilation of first-hand accounts (felt reports) describing aftershocks and triggered events of...

Magma intrusions and eruptions commonly produce abrupt changes in seismicity far from magma conduits1,2,3,4 that cannot be associated with the diffusion of pore fluids or heat5. Such ‘swarm’ seismicity also migrates with time, and often exhibits a ‘dog-bone’-shaped distribution3,4,6,7,8,9. The largest earthquakes in swarms produce aftershocks that obey an Omori-type (exponential)...

The Los Angeles Region Seismic Experiment (LARSE), a joint project of the U.S. Geological Survey (USGS) and the Southern California Earthquake Center (SCEC), was conducted to produce seismic images of the subsurface in the Los Angeles region. Primary targets were major fault systems and sedimentary basins; the goal of the project was to address the earthquake hazard posed by these...