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A preliminary study of the Santa Barbara, California, earthquake of August 13, 1978, and its major aftershocks

Circular 797

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Abstract

The ML5.1 Santa Barbara earthquake of August 13, 1978 occurred at lat 34 ? 22.2'N., long 119 ? 43.0' 4 km south of Santa Barbara, Calif. at a depth of 12.5 km in the northeast Santa Barbara Channel, part of the western Transverse Ranges geomorphic-structural province. This part of the province is characterized by seismically active, east-trending reverse faults and rates of coastal uplift that have averaged up to about 10 m/1000 years over the last 45,000 years. No surface rupture was detected onshore. Subsurface rupture propagated northwest from the main shock toward Goleta, 15 km west of Santa Barbara, where a maximum acceleration of 0.44 g was measured at ground level and extensive minor damage occurred; only minor injuries were reported. A fairly well-constrained fault-plane solution of the main shock and distribution of the aftershocks indicate that left-reverse-oblique slip occurred on west-northwest-trending, north-dipping reverse faults; inadequate dip control precludes good correlation with any one of several mapped faults. Had the earthquake been larger and rupture propagated to the southeast or a greater distance to the northwest, it could have posed a hazard to oilfield operations. The fault-plane solution and aftershock pattern closely fit the model of regional deformation and the solution closely resembles those of five previously mapped events located within a 15-km radius.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
A preliminary study of the Santa Barbara, California, earthquake of August 13, 1978, and its major aftershocks
Series title:
Circular
Series number:
797
Edition:
-
Year Published:
1978
Language:
ENGLISH
Publisher:
U.S. Dept. of the Interior, Geological Survey ; free on application to Branch of Distribution,
Description:
iii, 11 p. :ill. ;27 cm.