Publications

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Shear-wave velocities within several hundred meters of Earth's surface are important in specifying earthquake ground motions for engineering design. Not only are the shearwave velocities used in classifying sites for use of modern building codes, but they are also used in site-specific studies of particularly significant structures. Many are the methods for estimating sub-surface shear...

The composition of methane hydrate, namely nw for CH4·nwH2O, was directly measured along the hydrate equilibrium boundary under conditions of excess methane gas. Pressure and temperature conditions ranged from 1.9 to 9.7 MPa and 263 to 285 K. Within experimental error, there is no change in hydrate composition with increasing pressure along the equilibrium boundary, but nw may show a...

A 1-kilometer-long (0.62-mile-long) seismic reflection and refraction profile collected at the National Aeronautics and Space Administration (NASA) Langley Research Center, Hampton, Va., provides a detailed image of part of the annular trough of the buried, 35-million-year-old Chesapeake Bay impact structure. This profile passes within 5 meters (m; 16.4 feet (ft)) of a 635.1-m-deep (2...

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The Mw 6.0 Parkfield earthquake struck central California at 17:15:14 UTC on 28 September 2004. The epicenter was located 11 km southeast of the rural town of Parkfield, adjacent to Gold Hill and on the San Andreas Fault (Figure 1). The California Integrated Seismic Network (CISN) reported that the hypocenter was located at 35.819°N, 120.364°W at a depth of 8.8 km. From the distribution...

On several occasions in recent memory California has experienced apparent clusters of earthquake activity that are too far apart to be considered related according to a classic taxonomy that includes foreshocks, mainshocks, and aftershocks. During a week-long period in July 1986, California experienced the M 6.0 North Palm Springs earthquake, the M 5.5 Oceanside earthquake, and a swarm...

We present an updated global earthquake catalogue for stable continental regions (SCRs; i.e. intraplate earthquakes) that is available on the Internet. Our database contains information on location, magnitude, seismic moment and focal mechanisms for over 1300 M (moment magnitude) ≥ 4.5 historic and instrumentally recorded crustal events. Using this updated earthquake database in...

Several anecdotal accounts provide compelling evidence that liquefaction occurred at several sites in Illinois during the 1811-1812 New Madrid sequence, as much as 250 km north of the New Madrid seismic zone (NMSZ). At one Wabash Valley location, sand blows are still evident near Big Prairie, Illinois, a location described in a particularly detailed and precise historic account. This...

This publication makes available a detailed trench log (sheets 1 and 2) of a 110-m trench we excavated in 2004 across a tectonic sag pond in the Hayward fault zone. Also included are revised stratigraphic unit descriptions from this fifth field season of subsurface investigation of the Hayward fault at Tyson's Lagoon (Tule Pond). Preliminary findings based on fieldwork done in 2000 have...