Publications
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A preliminary summary of a seismic-refraction survey in the vicinity of the Tonto Forest Observatory, Arizona
The U.S. Geological Survey complete d a seismic-refraction survey in the vicinity of the Tonto Forest Seismological Observatory (T.F.S.O.) in April and May 1964. More than 1200 km of reversed profiles were surveyed to determine the crustal structure and crustal and upper mantle velocities in this area. The purpose of this work was to provide information on wave-propagation paths of seismic events
Authors
J.C. Roller, W. H. Jackson, D. H. Warren, J. H. Healy
Crustal structure between Lake Mead, Nevada, and Mono Lake, California
Interpretation of a reversed seismic-refraction profile between Lake Mead, Nevada, and Mono Lake, California, indicates velocities of 6.15 km/sec for the upper layer of the crust, 7.10 km/sec for an intermediate layer, and 7.80 km/sec for the uppermost mantle. Phases interpreted to be reflections from the top of the intermediate layer and the Mohorovicic discontinuity were used with the refraction
Authors
Lane R. Johnson
Seismic-refraction measurements of crustal structure between American Falls Reservoir, Idaho, and Flaming Gorge Reservoir, Utah
Interpretation of a reversed seismic-refraction profile recorded between American Falls reservoir and Flaming Gorge reservoir in May 1963 indicates that the depth to the Mohorovicic discontinuity is about 31 km at American Falls and 37 km at Flaming Gorge. The existence of an intermediate crustal layer at a depth of about 19 to 21 km beneath the profile is well supported by refractions and reflect
Authors
Ronald Willden
Variations in regional traveltimes
Precise epicentral location of a seismic event is made difficult by variations in regional traveltimes. A discussion is presented on delays to be expected in the various segments of a generalized travel path of seismic waves. Traveltime variations caused by changes in crustal structure and velocity introduce a major part of the uncertainty in traveltime at both the seismic source and receiver. Con
Authors
J. H. Healy
Continental crust
The structure of the Earth’s crust (the outer shell of the earth above the M-discontinuity) has been intensively studied in many places by use of geophysical methods. The velocity of seismic compressional waves in the crust and in the upper mantle varies from place to place in the conterminous United States. The average crust is thick in the eastern two-thirds of the United States, in which the cr
Authors
L. C. Pakiser
Compilation of seismic-refraction crustal data in the Soviet Union
The U.S. Geological Survey is preparing a series of terrain atlases of the Sino-Soviet bloc of nations for use in a possible nuclear-test detection program. Part of this project is concerned with the compilation and evaluation of crustal-structure data. To date, a compilation has been made of data from Russian publications that discuss seismic refraction and gravity studies of crustal structure. A
Authors
Robert Rodriguez, William P. Durbin, J. H. Healy, David H. Warren
Crustal structure in the eastern Colorado Plateaus Provence from seismic-refraction measurements
A reversed seismic-refraction profile was recorded in the Colorado Plateaus Province from Hanksville, Utah, to Chinle, Arizona, The velocity of Pg is 6.2 km/sec, and the true velocity of Pn is 7.8 km/sec, Waves identified as reflections indicate that an intermediate layer in the crust has a velocity of approximately 6.8 km/sec. Thickness of the crust is 43 km at Chinle and 40 km at Hanksville. The
Authors
John C. Roller
Preliminary report on some factors affecting shotpoint efficiency
A study of first-arrival amplitudes from 6 water shotpoints and 7 drill-hole shotpoints in parts of central and western United States indicate a variation of over 100 to 1 between the best and poorest shotpoints. Water shotpoints are, in general, superior to drill-hole shotpoints; however, one drill-hole shotpoint produced higher signal amplitudes than more than half of the water shotpoints. Signa
Authors
W. H. Jackson, J. H. Healy
Preliminary report on the geologic and geophysical investigations of the Loveland Basin landslide, Clear Creek County, Colorado
No abstract available.
Authors
Charles Sherwood Robinson, Fitzhugh T. Lee, R. D. Carroll
Preliminary study of first motion from nuclear explosions recorded on seismograms in the first zone
The U.S. Geological Survey has recorded more than 300 seismograms from more than 50 underground nuclear explosions. Most were recorded at distances of less than 1,000 km. These seismograms have been studied to obtain travel times and amplitudes which have been presented in reports on crustal structure and in a new series of nuclear shot reports. This report describes preliminary studies of first m
Authors
J. H. Healy, G. B. Mangan
Crustal structure in the vicinity of Las Vegas, Nevada, from seismic and gravity observations
A seismic-refraction profile indicates that the crust of the Earth increases in thickness by as much as 5 km over a horizontal distance of less than 25 km northeast of Las Vegas, Nevada. This feature correlates with a decrease in the Bouguer anomaly and an increase in the average surface altitude.
Authors
John C. Roller
Crustal structure from San Francisco, California, to Eureka, Nevada, from seismic-refraction measurements
Seismic-refraction measurements from chemical explosions near San Francisco, California, and Fallon and Eureka, Nevada, were made along a line extending nearly 700 km inland from San Francisco across the Coast Ranges, Great Valley, Sierra Nevada, and Basin and Range Province. The velocity of Pg in the Basin and Range Province was found to be 6.0 km/sec. Between Fallon and Eureka the velocity of Pn
Authors
Jerry P. Eaton