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The 2010 M_w 7.2 El Mayor-Cucapah Earthquake Sequence, Baja California, Mexico and Southernmost California, USA: Active Seismotectonics along the Mexican Pacific Margin

Hauksson, Egill and Stock, Joann and Hutton, Kate and Yang, Wenzheng and Vidal-Villegas, J. Antonio and Kanamori, Hiroo (2011) The 2010 M_w 7.2 El Mayor-Cucapah Earthquake Sequence, Baja California, Mexico and Southernmost California, USA: Active Seismotectonics along the Mexican Pacific Margin. Pure and Applied Geophysics, 168 (8-9). pp. 1255-1277. ISSN 0033-4553. doi:10.1007/s00024-010-0209-7.

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The El Mayor-Cucapah earthquake sequence started with a few foreshocks in March 2010, and a second sequence of 15 foreshocks of M > 2 (up to M4.4) that occurred during the 24 h preceding the mainshock. The foreshocks occurred along a north–south trend near the mainshock epicenter. The M_w 7.2 mainshock on April 4 exhibited complex faulting, possibly starting with a ~M6 normal faulting event, followed ~15 s later by the main event, which included simultaneous normal and right-lateral strike-slip faulting. The aftershock zone extends for 120 km from the south end of the Elsinore fault zone north of the US–Mexico border almost to the northern tip of the Gulf of California. The waveform-relocated aftershocks form two abutting clusters, each about 50 km long, as well as a 10 km north–south aftershock zone just north of the epicenter of the mainshock. Even though the Baja California data are included, the magnitude of completeness and the hypocentral errors increase gradually with distance south of the international border. The spatial distribution of large aftershocks is asymmetric with five M5+ aftershocks located to the south of the mainshock, and only one M5.7 aftershock, but numerous smaller aftershocks to the north. Further, the northwest aftershock cluster exhibits complex faulting on both northwest and northeast planes. Thus, the aftershocks also express a complex pattern of stress release along strike. The overall rate of decay of the aftershocks is similar to the rate of decay of a generic California aftershock sequence. In addition, some triggered seismicity was recorded along the Elsinore and San Jacinto faults to the north, but significant northward migration of aftershocks has not occurred. The synthesis of the El Mayor-Cucapah sequence reveals transtensional regional tectonics, including the westward growth of the Mexicali Valley and the transfer of Pacific–North America plate motion from the Gulf of California in the south into the southernmost San Andreas fault system to the north. We propose that the location of the 2010 El Mayor-Cucapah, as well as the 1992 Landers and 1999 Hector Mine earthquakes, may have been controlled by the bends in the plate boundary.

Item Type:Article
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URLURL TypeDescription
Hauksson, Egill0000-0002-6834-5051
Stock, Joann0000-0003-4816-7865
Kanamori, Hiroo0000-0001-8219-9428
Additional Information:© 2010 Springer Basel AG. Received July 10, 2010, revised September 1, 2010, accepted September 6, 2010, Published online November 16, 2010. This research was supported by the US Geological Survey Grant G10AP00017; NSF grants EAR-0911761 and OCE-0742253 to Caltech, and by the Southern California Earthquake Center. SCEC is funded by NSF Cooperative Agreement EAR-0529922 and USGS Cooperative Agreement 07HQAG0008. The Incorporated Research Institutions for Seismology (IRIS) Data Management System (DMS) was used to access the Global Seismographic Network data. Funds for maintenance of RESNOM network are provided by CICESE. We thank S. Wei, S. Skinner, and E. Glowacka for feedback and discussions. We thank L. Munguía, G. Diaz, F. Farfan, I. Mendez, L. Orozco, O. Galvez, and S. Arregui, Department of Seismology, CICESE, Baja California, Mexico, and N. Scheckel, A. Guarino, and B. Wu of the SCSN for help with data collection and processing. Most figures were done using GMT (WESSEL and SMITH, 1998). SCEC contribution number 1,439. Contribution number 10,047, Seismological Laboratory, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena.
Group:Seismological Laboratory, Division of Geological and Planetary Sciences
Funding AgencyGrant Number
Southern California Earthquake Center (SCEC)UNSPECIFIED
Subject Keywords:Seismicity, El Mayor-Cucapah earthquake, Mexican Pacific Margin, Baja California, Southern California, faults, aftershocks, seismotectonics, margin processes, Pacific–North America plate boundary, tomography
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Other Numbering System NameOther Numbering System ID
Southern California Earthquake Center (SCEC)1439
Caltech Seismological Laboratory 10,047
Issue or Number:8-9
Record Number:CaltechAUTHORS:20110802-141212219
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:24633
Deposited By: Ruth Sustaita
Deposited On:02 Aug 2011 22:25
Last Modified:09 Nov 2021 16:25

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