Publications

A 275‐km‐long reversed refraction profile in the Oregon Cascades, two shallow earthquakes of magnitude 5 in southern Washington, a shallow earthquake of magnitude 4.6 in northern California, and a previously published analysis of the Bouguer gravity field are used to develop a crustal P wave velocity model for the Oregon Cascades. Travel time analysis of the refraction profile indicates...

The U.S. Geological Survey conducted an extensive seismic refraction survey in the Imperial Valley region of California in 1979. The Imperial Valley is located in the Salton Trough, an active rift between the Pacific and North American plates. Forty shots fired at seven shot points were recorded by 100 portable seismic instruments at typical spacing of 0.5–1 km. More than 1300 recording...

The important role of pore pressure in promoting such brittle processes as cataclasis, hydraulic fracturing, large‐scale faulting, and earthquakes within the crust is widely accepted in geology and geophysics [, 1957; , 1959; , 1958; ., 1963; , 1968; ., 1968; ., 1976; , 1973, 1980; , 1981]. Provided that fluid pressure is fully communicated with rock pore space, the effective normal...

Crystallographically oriented single‐crystal prisms of gem quality topaz (composition AlSiO (OH− F) where x = 0.04 ± 0.01) were deformed at a confining pressure of 1.50 GPa, a temperature of 800°C, and a strain rate of 2×10 s. Under nearly identical conditions, all crystals of anhydrous rock‐forming minerals that have been tested to date, such as olivine, quartz, feldspars, pyroxenes...

A hydrothermally grown synthetic quartz crystal with 370±60 ppm hydroxyl impurity was cut into right rectangular prisms in eight crystallographic orientations. We compressed the prisms under constant axial force corresponding to a uniaxial stress of 140.0±0.5 MPa, and temperatures of 510° and 750°C. All but one of the samples sustained permanent axial strains of 2–3%. We established the...

The seismic networks have been designed and operated to support recording on Develocorders (less than 40db dynamic range) and analog magnetic tape (about 50 db dynamic range). The principal analysis of the records has been based on Develocorder films; and background earth noise levels have been adjusted to be about 1 to 2 mm p-p on the film readers. Since the traces are separated by only...

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A profile of the strain accumulation rate along a line trending N50°E across the subparallel Elsinore, San Jacinto, and San Andreas faults near Palm Springs, California, has been constructed from trilateration surveys in the 1973‐81 interval. The strain accumulation is principally right‐lateral shear across a vertical plane parallel to fault strike (N40°W). The strain rate profile for...

Jackson and Cheng have suggested that the changes in areal dilatation measured in Geodolite surveys by the U.S. Geological Survey may be simply an artifact of the measuring system. Although systematic error could conceivably account for the observed excursions in dilatation, we maintain that the specific criticisms by Jackson and Cheng are incorrect: the excursions in dilatation cannot...

This review is principally concerned with recent geodetic strain measurements in western United States undertaken by the US Geological Survey as part of the earthquake studies program and, as a consequence, is heavily biased toward the author's own publications. Most of the publications reporting crustal-strain measurements in western United States prior to about 1968 have been compiled...