Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by HAUKSSON, E. Articles by SALDIVAR, G. V. Search for Related Content GeoRef GeoRef Citation

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

DEPARTMENT OF GEOLOGICAL SCIENCES UNIVERSITY OF SOUTHERN CALIFORNIA, LOS ANGELES, CALIFORNIA 90089-0741

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 x 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.

This article has been cited by other articles:

				M. A. Fisher, W. R. Normark, V. E. Langenheim, A. J. Calvert, and R. Sliter The Offshore Palos Verdes Fault Zone near San Pedro, Southern California Bulletin of the Seismological Society of America, April 1, 2004; 94(2): 506 - 530. [Abstract] [Full Text] [PDF]

				Geology of the Continental Margin beneath Santa Monica Bay, Southern California, from Seismic-Reflection Data Bulletin of the Seismological Society of America, October 1, 2003; 93(5): 1955 - 1983.

				H. Tsutsumi, R. S. Yeats, and G. J. Huftile Late Cenozoic tectonics of the northern Los Angeles fault system, California Geological Society of America Bulletin, April 1, 2001; 113(4): 454 - 468. [Abstract] [Full Text] [PDF]

				Earthquake Locations in the Inner Continental Borderland, Offshore Southern California Bulletin of the Seismological Society of America, April 1, 2000; 90(2): 425 - 449.

				J. F. Dolan, J. F. Dolan, K. Sieh, T. K. Rockwell, R. S. Yeats, J. Shaw, J. Suppe, G. J. Huftile, and E. M. Gath Prospects for Larger or More Frequent Earthquakes in the Los Angeles Metropolitan Region Science, January 13, 1995; 267(5195): 199 - 205. [Abstract] [PDF]

				E. Hauksson, E. HAUKSSON, L. M. JONES, T. L. DAVIS, L. K. HUTTON, P. WILLIAMS, A. L. BENT, A. G. BRADY, P. A. REASENBERG, A. J. MICHAEL, et al. The 1987 Whittier Narrows Earthquake in the Los Angeles Metropolitan Area, California Science, March 18, 1988; 239(4846): 1409 - 1412. [Abstract] [PDF]