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Crustal structure in the western United States; study of seismic propagation paths and regional traveltimes in the California-Nevada region

Crustal Studies Technical Letter 9

In cooperation with the Defense Advanced Research Projects Agency
By:
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Abstract

The U.S. Geological Survey, with the assistance of United ElectroDynamics, Inc., completed ten weeks of seismic-refraction field work during the summer of 1962 in the southwestern part of the United States. This work was a continuation of a program initiated in 1961 to study traveltimes and seismic propagation paths in the earth?s crust and upper mantle in the western United States. A total of 761 seismograms were recorded along 10 profiles from 86 explosions at 18 shotpoints. Analysis of the data is continuing, but a few conclusions can be made from a preliminary study: (1) Variations in traveltimes in the Basin and Range province are large but measurable, and perhaps predictable. (2) Traveltimes of seismic waves in adjacent geologic provinces are usually significantly different. (3) The velocity of Pg along all of the profiles recorded in 1962 ranges from 5.0 to 6.5 km/sec, and averages 6.0 km/sec. (4) The average velocity of Pg in extreme northern Nevada and southern Idaho is 5.6 km/sec, and it is 6.1 km/sec in most of Nevada and California. (5) The average velocity of Pn is 7–9 km/ sec and ranges from 7.85 to 7.95 km/sec on reversed profiles where the true Pn velocity could be computed. (6) A shallow "intermediate" layer with a velocity of approximately 6.8 km/sec was found in the Snake River Plain. (7) Refraction arrivals from the mantle (Pn) were recorded in the Sierra Nevada. They indicate that the thickness of the crust in the Sierra Nevada is much greater than that in the Basin and Range province. (8) Many refinements in field techniques were made during the 1962 field season.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Unnumbered Series
Title:
Crustal structure in the western United States; study of seismic propagation paths and regional traveltimes in the California-Nevada region
Series title:
Crustal Studies Technical Letter
Series number:
9
Year Published:
1963
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
Earthquake Science Center
Description:
57 p.; ill.; maps
First page:
1
Last page:
57
Country:
United States
State:
California;Nevada;Idaho
Online Only (Y/N):
Y
Additional Online Files(Y/N):
N