Publications
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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
Venus cartography
The entire surface of the planet Venus is being mapped at global and regional scales (1:50,000,000 through 1:1,500,000) with synthetic aperture radar (SAR), radar altimeter, and radiometer measurements of physical properties from the Magellan spacecraft. The mapping includes SAR image mosaics, shaded relief maps, and topographic contour overlays made from altimetry data and by radargrammetric meth
Authors
R. M. Batson, Randolph L. Kirk, Kathleen Edwards, H.F. Morgan
Evaluation of an empirical radar backscatter model for predicting backscatter characteristics of geologic units at Pisgah Volcanic Field, California
Comparison of radar backscatter coefficients (σ°, in dB), calculated by using the empirical model of Oh et al. [1992], to σ° extracted from AIRSAR data of four geologic units at Pisgah shows that the model predicts measured σ°vv and σ°hv to within ±3 dB. The model predicts higher σ°hh than those observed. For smooth surfaces (rms height=s, s<8 cm), model results depend strongly on the accuracy of
Authors
Lisa R. Gaddis
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
Some observations of landslides triggered by the 29 April 1991 Racha earthquake, Republic of Georgia
On 29 April 1991 an Ms 7.0 earthquake occurred in the Racha region of the Great Caucasus Mountains in north-central Republic of Georgia. The earthquake occurred on a thrust fault striking roughly east-west and dipping about 20° to 45° northward; focal depth was 17 ± 2 km. We observed no surface fault rupture, but the earthquake caused extensive structural damage to the many unreinforced stone buil
Authors
R. W. Jibson, C. S. Prentice, B.A. Borissoff, E.A. Rogozhin, C.J. Langer
USGS coastal studies in the northeastern Gulf of Mexico
No abstract available.
Authors
Guy R. Gelfenbaum
The volcanic, sedimentologic, and paleolimnologic history of the Crater Lake caldera floor, Oregon:Evidence for small caldera evolution
Apparent phreatic explosion craters, caldera-floor volcanic cones, and geothermal features outline a ring fracture zone along which Mount Mazama collapsed to form the Crater Lake caldera during its climactic eruption about 6,850 yr B.P. Within a few years, subaerial deposits infilled the phreatic craters and then formed a thick wedge (10-20 m) of mass flow deposits shed from caldera walls. Intense
Authors
C. Hans Nelson, Charles R. Bacon, Stephen W. Robinson, David P. Adam, J. Platt Bradbury, John H. Barber, Deborah Schwartz, Ginger Vagenas
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