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Postseismic deformation following the 1989 (M = 7.1): Loma Prieta, California, earthquake

December 11, 1994

Postseismic deformation along a 90‐km profile bisecting the projected surface trace of the coseismic rupture of the 1989 Loma Prieta earthquake has been monitored by frequent GPS surveys for 3.3 years following the earthquake. In addition to the expected deformation associated with secular strain accumulation on the San Andreas and Calaveras faults, deformation associated with postseismic readjustment has been detected. Most of that deformation can be attributed to 1.5 m right‐lateral and 0.9 m reverse postseismic slip on a 5‐km‐wide downdip extension of the Loma Prieta rupture. In addition, there seems to be a 0.1 m postseismic collapse of the Loma Prieta rupture zone in the direction perpendicular to the plane of the rupture. The fault‐normal (N48°E) surface displacements plotted as a function of time exhibit a curvature suggesting a relaxation time of about 1.4 years. Similar plots of the fault‐parallel (N42°W) displacement components do not exhibit significant curvature. Presumably, the deformation shown in those plots is dominated by secular strain accumulation along the San Andreas and Calaveras faults rather than postseismic relaxation.

Citation Information

Publication Year 1994
Title Postseismic deformation following the 1989 (M = 7.1): Loma Prieta, California, earthquake
DOI 10.1029/94JB00507
Authors James C. Savage, Michael Lisowski, Jerry L. Svarc
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Geophysical Research B: Solid Earth
Index ID 70207170
Record Source USGS Publications Warehouse
USGS Organization Earthquake Science Center

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