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Temporal variation of seismicity and spectrum of small earthquakes preceding the 1952 Kern County, California, earthquake

Ishida, Mizuho and Kanamori, Hiroo (1980) Temporal variation of seismicity and spectrum of small earthquakes preceding the 1952 Kern County, California, earthquake. Bulletin of the Seismological Society of America, 70 (2). pp. 509-527. ISSN 0037-1106. https://resolver.caltech.edu/CaltechAUTHORS:20140814-084253849

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Abstract

The spatio-temporal variation of seismicity in the epicentral area of the 1952 Kern County California, earthquake (M_s = 7.7, 34°58.6′N; 119°02′W) was examined for the period prior to the main shock. Most of the events that occurred in the epicentral area were relocated by using the main shock as a master event. A large part of the fault plane of the Kern County earthquake had been seismically quiet for nearly 15 yr before the main shock. However, the activity in the immediate vicinity of the epicenter had been very high during the same period. The temporal variation of the activity in the vicinity of the epicentral area exhibits a pattern very similar to that found for the 1971 San Fernando earthquake. During the 1 1/2 yr period immediately before the main shock, tight clustering of activity around the main-shock epicenter occurred. This clustering may be considered to be foreshock activity. This period of increased activity was preceded by a quiet period for 2 yr from 1949 to 1950; no event was located on the fault plane of the Kern County earthquake during this period. This pattern, quiescence followed by clustering, seems to have repeated several times prior to 1949. Thus, this pattern alone cannot be used as a definite indicator of a large earthquake, but in terms of a fault model with asperities, it can be a manifestation of progressive stress concentration toward the eventual hypocenter. Spectral analyses of the Pasadena Wood-Anderson seismograms of the events that occurred near the epicentral area showed that the frequency of the spectral peak is systematically higher for the foreshocks than the events prior to 1949. A similar trend was found for the 1971 San Fernando earthquake. These results are consistent with the model of stress concentration around the eventual hypocenter.


Item Type:Article
Related URLs:
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http://www.bssaonline.org/content/70/2/509.abstract?related-urls=yes&legid=ssabull;70/2/509PublisherArticle
ORCID:
AuthorORCID
Kanamori, Hiroo0000-0001-8219-9428
Additional Information:© 1979 Seismological Society of America. Manuscript received May 16, 1979. We thank Kazuya Fujita, Tracy Johnson, and Don Anderson for valuable comments. This research was funded by U.S. Geological Survey Contract 14-08-0001-17631. Mizuho Ishida was partially supported by a fellowship from the Science and Technology Agency in Japan.
Funders:
Funding AgencyGrant Number
USGS14-08-0001-17631
Japan Science and Technology AgencyUNSPECIFIED
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Caltech Division of Geological and Planetary Sciences3216
Issue or Number:2
Record Number:CaltechAUTHORS:20140814-084253849
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140814-084253849
Official Citation:Ishida, M., & Kanamori, H. (1980). Temporal variation of seismicity and spectrum of small earthquakes preceding the 1952 Kern County, California, earthquake. Bulletin of the Seismological Society of America, 70(2), 509-527.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:48543
Collection:CaltechAUTHORS
Deposited By:INVALID USER
Deposited On:14 Aug 2014 20:42
Last Modified:09 Mar 2020 13:18

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