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Coseismic deformation during the 1989 Loma Prieta earthquake and range-front thrusting along the southwestern margin of the Santa Clara Valley, California

January 1, 1997

Damage patterns caused by the 1989 Loma Prieta earthquake along the southwestern margin of the Santa Clara Valley, California, form three zones that coincide with mapped and inferred traces of range-front thrust faults northeast of the San Andreas fault. Damage in these zones was largely contractional, consistent with past displacement associated with these faults. The damage zones coincide with gravity and aeromagnetic anomalies; modeling of the anomalies defines a southwest-dipping thrust fault that places the Franciscan Complex over Cenozoic sedimentary rocks to minimum depths of 2 km. Diffuse Loma Prieta earthquake aftershocks encompass the downward projection of this modeled thrust to depths of 9 km. Our results indicate that in this region the potential for concentrated damage arising from either primary deformation along the thrust faults themselves or by sympathetic motion triggered by earthquakes on the San Andreas fault may be higher than previously recognized.

Citation Information

Publication Year 1997
Title Coseismic deformation during the 1989 Loma Prieta earthquake and range-front thrusting along the southwestern margin of the Santa Clara Valley, California
DOI 10.1130/0091-7613(1997)025<1091:CDDTLP>2.3.CO;2
Authors V. E. Langenheim, K. M. Schmidt, R. C. Jachens
Publication Type Article
Publication Subtype Journal Article
Series Title Geology
Series Number
Index ID 70019685
Record Source USGS Publications Warehouse
USGS Organization Geology, Minerals, Energy, and Geophysics Science Center