Crustal structure along the coast of California from seismic-refraction measurements

Crustal Studies Technical Letter 5
In cooperation with the Defense Advanced Research Projects Agency



Two reversed seismic-refraction profiles were recorded between Los Angeles and San Francisco in 1961. The three shotpoints were located in Santa Monica Bay, offshore near San Francisco, and at Camp Roberts, about halfway between Los Angeles and San Francisco. The velocity of Pg along these profiles is 6.1 ± 0.1 km/sec, with possible exceptions near San Francisco and near Los Angeles, where the scatter in the arrival times indicates complex near-surface velocity variations. The velocity of Pn between Los Angeles and Camp Roberts is 8.2 ± 0.1 km/sec, and between Camp Roberts and San Francisco 8.0 ± 0.2 km/sec. There is no indication of an intermediate crustal layer in the traveltimes of first arrivals. Computed depths to the Mohorovicic discontinuity, if the crust consists of a single layer, are: 35 km at Los Angeles, 23 km at Camp Roberts, and 23 km at San Francisco. Refractions from crustal layers of intermediate velocity need not appear as first arrivals, and in the extreme, the depth to the Mohorovicic discontinuity may be one-third greater than the thickness of a one-layer crust.
Publication type Report
Publication Subtype USGS Unnumbered Series
Title Crustal structure along the coast of California from seismic-refraction measurements
Series title Crustal Studies Technical Letter
Series number 5
DOI 10.3133/70039278
Year Published 1962
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Earthquake Science Center
Description 30 p.
First page 1
Last page 30
Country United States
State California
Other Geospatial Santa Monica Bay
Online Only (Y/N) Y
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details