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The 1930 Santa Monica and the 1979 Malibu, California, earthquakes

Hauksson, Egill and Saldivar, Geoffrey V. (1986) The 1930 Santa Monica and the 1979 Malibu, California, earthquakes. Bulletin of the Seismological Society of America, 76 (6). pp. 1542-1559. ISSN 0037-1106. http://resolver.caltech.edu/CaltechAUTHORS:20130306-093442744

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Abstract

The Malibu earthquake (M_L = 5.0) that occurred 1 January 1979 in Santa Monica Bay was located at 33°56.9′N and 118°41.3′W and at a depth of 10 km. The focal mechanism of the main shock as determined from first motions recorded by short-period, high-gain seismic stations in southern California shows reverse faulting with one plane dipping 55° to 60° to the north striking 275° to 290°, and the second plane dipping 30° to 38° to the south and striking 100° to 120°. More than 400 aftershocks were recorded during 1979. Focal mechanisms for 20 aftershocks of M ≧ 3.0 show similar reverse mechanisms as the main shock. The main shock and aftershocks (M ≧ 2.5) were relocated using a local velocity model and a set of corresponding station delays. The aftershocks define a volumetric hypocentral zone, 4 km × 6 km, west-trending with depths ranging from 6 to 11 km. This 1979 Malibu main shock-aftershock sequence probably occurred on the eastern end of the Anacapa-Dume fault. The Santa Monica earthquake (M_L = 5.2) that occurred 31 August 1930 was relocated using station delays calculated from the 1979 date set. The relocated 1930 epicenter is located near the western end of the Santa Monica fault. The 1979 and 1930 main shocks can be interpreted to define a 8- to 10-km north-south sidestep between the Anacapa-Dume and Santa Monica faults. Possible segmentation of these two fault systems suggests that they are unlikely to rupture simultaneously in one large earthquake.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://bssa.geoscienceworld.org/content/76/6/1542.abstractPublisherArticle
ORCID:
AuthorORCID
Hauksson, Egill0000-0002-6834-5051
Additional Information:© 1986 Seismological Society of America. Manuscript received 14 April 1986. We are indebted to Lucile M. Jones for making copies of the CIT/USGS southern California network data available and for critical reviews. We also thank John K. McRaney for reviewing the manuscript. Copies of photographic records and phase cards of the 1930 and 1979 main shocks were provided by Paul Roberts of Caltech. This research was supported by USGS Grants 14-08-0001-G983 and -G1158 and USGS Contract 14-08-0001-21858. The figures were drafted by Janet Dodds and the manuscript typed by Sue Turnbow.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
USGS14-08-0001-G983
USGS14-08-0001-G1158
USGS14-08-0001-21858
Record Number:CaltechAUTHORS:20130306-093442744
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20130306-093442744
Official Citation:Egill Hauksson and Geoffrey V. Saldivar The 1930 Santa Monica and the 1979 Malibu, California, earthquakes Bulletin of the Seismological Society of America, December 1986, v. 76, p. 1542-1559
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37337
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:06 Mar 2013 18:32
Last Modified:24 Jan 2016 22:31

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