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A possible geodetic anomaly observed prior to the Loma Prieta, California, Earthquake

December 6, 1990

Monthly measurements since mid‐1981 of distance from a geodetic station located 11 km from the epicenter of the Loma Prieta earthquake (Ms = 7.1; October 17, 1989) to three stations 30 to 40 km distant provides an unusually complete record of deformation in the epicentral region in the years prior to an earthquake. Roughly 1.3 years before the earthquake, at about the time of the first magnitude‐5 foreshock, the rate of change in line length for two of the lines appears to change; the rate for the third line does not change. Other similar, though smaller, changes in rate are apparent in the eight‐year record. Thus, there is marginal evidence for a change in deformation rate about one year before the Loma Prieta earthquake, but that change need not be a precursor.

Citation Information

Publication Year 1990
Title A possible geodetic anomaly observed prior to the Loma Prieta, California, Earthquake
DOI 10.1029/GL017i008p01211
Authors Michael Lisowski, W. H. Prescott, James C. Savage, Jerry L. Svarc
Publication Type Article
Publication Subtype Journal Article
Series Title Geophysical Research Letters
Index ID 70207098
Record Source USGS Publications Warehouse
USGS Organization Earthquake Science Center

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