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Basin structure beneath the Santa Rosa Plain, Northern California: Implications for damage caused by the 1969 Santa Rosa and 1906 San Francisco earthquakes

Bulletin of the Seismological Society of America

By:
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DOI: 10.1785/0120060269

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Abstract

Regional gravity data in the northern San Francisco Bay region reflect a complex basin configuration beneath the Santa Rosa plain that likely contributed to the significant damage to the city of Santa Rosa caused by the 1969 M 5.6, 5.7 Santa Rosa earthquakes and the 1906 M 7.9 San Francisco earthquake. Inversion of these data indicates that the Santa Rosa plain is underlain by two sedimentary basins about 2 km deep separated by the Trenton Ridge, a shallow west-northwest-striking bedrock ridge west of Santa Rosa. The city of Santa Rosa is situated above the 2-km-wide protruding northeast corner of the southern basin where damage from both the 1969 and 1906 earthquakes was concentrated. Ground-motion simulations of the 1969 and 1906 earthquakes, two events with opposing azimuths, using the gravity-defined basin surface, show enhanced ground motions along the northeastern edge of this corner, suggesting that basin-edge effects contributed to the concentration of shaking damage in this area in the past and may also contribute to strong shaking during future earthquakes.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Basin structure beneath the Santa Rosa Plain, Northern California: Implications for damage caused by the 1969 Santa Rosa and 1906 San Francisco earthquakes
Series title:
Bulletin of the Seismological Society of America
DOI:
10.1785/0120060269
Volume
97
Issue:
5
Year Published:
2007
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
1449
Last page:
1457
Number of Pages:
9