Chapter D. The Loma Prieta, California, Earthquake of October 17, 1989 - Aftershocks and Postseismic Effects

Professional Paper 1550- D
Prepared in cooperation with the National Science Foundation
Edited by: Paul A. Reasenberg



While the damaging effects of the earthquake represent a significant social setback and economic loss, the geophysical effects have produced a wealth of data that have provided important insights into the structure and mechanics of the San Andreas Fault system. Generally, the period after a large earthquake is vitally important to monitor. During this part of the seismic cycle, the primary fault and the surrounding faults, rock bodies, and crustal fluids rapidly readjust in response to the earthquake's sudden movement. Geophysical measurements made at this time can provide unique information about fundamental properties of the fault zone, including its state of stress and the geometry and frictional/rheological properties of the faults within it. Because postseismic readjustments are rapid compared with corresponding changes occurring in the preseismic period, the amount and rate of information that is available during the postseismic period is relatively high. From a geophysical viewpoint, the occurrence of the Loma Prieta earthquake in a section of the San Andreas fault zone that is surrounded by multiple and extensive geophysical monitoring networks has produced nothing less than a scientific bonanza. The reports assembled in this chapter collectively examine available geophysical observations made before and after the earthquake and model the earthquake's principal postseismic effects. The chapter covers four broad categories of postseismic effect: (1) aftershocks; (2) postseismic fault movements; (3) postseismic surface deformation; and (4) changes in electrical conductivity and crustal fluids.

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Chapter D. The Loma Prieta, California, Earthquake of October 17, 1989 - Aftershocks and Postseismic Effects
Series title Professional Paper
Series number 1550
Chapter D
DOI 10.3133/pp1550D
Edition -
Year Published 1997
Language ENGLISH
Publisher Geological Survey (U.S.)
Contributing office(s) Earthquake Hazards Program
Description p. D1-D312
Larger Work Type Report
Larger Work Subtype USGS Numbered Series
Larger Work Title The Loma Prieta, California, Earthquake of October 17, 1989: Earthquake Occurrence