Publications
Filter Total Items: 2585
Averting Surprises in the Pacific Northwest
No abstract available.
Authors
Brian F. Atwater, Thomas S. Yelin, Craig S. Weaver, James W. Hendley
San Andreas fault zone drilling project: scientific objectives and technological challenges
We are leading a new international initiative to conduct scientific drilling within the San Andreas fault zone at depths of up to 10 km. This project is motivated by the need to understand the physical and chemical processes operating within the fault zone and to answer fundamental questions about earthquake generation along major plate-boundary faults. Through a comprehensive program of coring, f
Authors
S.H. Hickman, L.W. Younker, M.D. Zoback
Strain accumulation along the Laguna Salada Fault, Baja California, Mexico
Strain accumulation observed over the 1978–1991 interval in a 30×100 km aperture trilateration network spanning the Laguna Salada fault is described by the principal strain rates 0.101±0.012 strain/yr N80°E±2° and −0.021±0.012 strain/yr N10°W±2°, extension reckoned positive. These strain accumulation rates have been corrected to remove coseismic effects of the nearby 1979 Imperial Valley ( = 6.5),
Authors
James C. Savage, Michael Lisowski, N.E. King, W.K. Gross
Postseismic deformation following the 1989 (M = 7.1): Loma Prieta, California, earthquake
Postseismic deformation along a 90‐km profile bisecting the projected surface trace of the coseismic rupture of the 1989 Loma Prieta earthquake has been monitored by frequent GPS surveys for 3.3 years following the earthquake. In addition to the expected deformation associated with secular strain accumulation on the San Andreas and Calaveras faults, deformation associated with postseismic readjust
Authors
James C. Savage, Michael Lisowski, Jerry L. Svarc
Strain accumulation north of Los Angeles, California, as a function of time, 1977–1992
No significant change in the rate of strain accumulation in a 40×120 km trilateration network spanning the San Gabriel mountains was observed from 1977.5 to 1991.8 despite an apparent increase in seismicity (ML > 4.5) beginning in late 1987 in the northern Los Angeles basin immediately to the south. The observed deformation (0.13±0.01 µstrain/yr right‐lateral shear across a vertical plane striking
Authors
James C. Savage, Michael Lisowski
Evidence for near-frictionless faulting in the 1989 (M 6.9) Loma Prieta, California, earthquake and its aftershocks: Comment and Reply
No abstract available.
Authors
James C. Savage, Mark D. Zoback, G. Beroza
Estimates of site-dependent response spectra for design (methodology and justification)
Recent borehole-geotechnical data and strong-motion measurements constitute a new empirical basis to account for local geological conditions in earthquake-resistant design and site-dependent, building-code provisions. They provide new unambiguous definitions of site classes and rigorous empirical estimates of site-dependent amplification factors in terms of mean shear-wave velocity. A simple four-
Authors
Roger D. Borcherdt
Evolution of the Precambrian lithosphere: Seismological and geochemical constraints
Several recent models of crustal evolution are based on the belief that the thickness of the continental crust is proportional to its age, with ancient crust being the thickest. A worldwide review of seismic structure contradicts this belief and falsifies these models, at least for the Archean. Proterozoic crust has a thickness of 40–55 km and a substantial high‐velocity (>7 km/s) layer at its bas
Authors
R. Durrheim, Walter D. Mooney
Crustal velocity structure of the northern Yukon-Tanana upland, central Alaska: Results from TACT refraction/wide-angle reflection data
The Fairbanks North seismic refraction/ wide-angle reflection profile, collected by the U.S. Geological Survey Trans-Alaska Crustal Transect (TACT) project in 1987, crosses the complex region between the Yukon-Tanana and Ruby terranes in interior Alaska. This region is occupied by numerous small terranes elongated in a northeast-southwest direction. These seismic data reveal a crustal velocity str
Authors
Bruce C. Beaudoin, Gary S. Fuis, William J. Lutter, Walter D. Mooney, Thomas E. Moore
Measurements of P and S wave fronts from the dense three-dimensional array at Garni, Armenia
The P- and S-wave arrivals from local earthquakes were studied using an array of 10 three-component instruments in and around a tunnel at Garni Observatory, Armenia. The array has a three-dimensional configuration with lateral dimensions of 300 to 500 m and a depth extent of 100 m. Estimates of the horizontal and vertical components of slowness for P and S wave fronts were used to determine the an
Authors
Jim Mori, John R. Filson, Edward Cranswick, Roger D. Borcherdt, Ruben Amirbekian, Vigen Aharonian, Leon Hachverdian
Crustal structure and composition of the southern Foothills Metamorphic Belt, Sierra Nevada, California, from seismic data
The Foothills Metamorphic Belt is an accreted terrane consisting of Paleozoic and Mesozoic metamorphic rocks that separates the Great Valley from the Sierra Nevada batholith in northern and central California. Until recently, the only available geophysical data for this area were reconnaissance refraction surveys, and gravity and magnetic data. New insights into the structure of the deep crust are
Authors
Kate Miller, Walter D. Mooney
Early warning system for aftershocks
A prototype early warning system to provide San Francisco and Oakland, California a few tens-of-seconds warning of incoming strong ground shaking from already-occurred M ≧ 3.7 aftershocks of the magnitude 7.1 17 October 1989 Loma Prieta earthquake was operational on 28 October 1989. The prototype system consisted of four components: ground motion sensors in the epicentral area, a central receiver,
Authors
W. H. Bakun, F.G. Fischer, E.G. Jensen, J. VanSchaack