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The AAPG/Datapages Combined Publications Database

AAPG Special Volumes


Pub. Id: A114 (1991)

First Page: 261

Last Page: 283

Book Title: M 47: The Gulf and Peninsular Province of the Californias

Article/Chapter: Crustal Structure and Seismotectonics of Northern Baja California: Chapter 15: Part III. Regional Geophysics and Geology

Subject Group: Geologic History and Areal Geology

Spec. Pub. Type: Memoir

Pub. Year: 1991

Author(s): J. Frez, J. J. Gonzalez


In the short historical record of northern Baja California, the largest earthquake has a magnitude 7.1. Most of the earthquakes with ML > 6.0 occur along the Cerro Prieto, Imperial, and San Miguel faults; no significant seismicity is known to have occurred along the Agua Blanca fault. A large part of the microseismicity (ML < 3.0) is sporadic, dominated by swarms, and in good correlation with mapped faults. Seismogenic depths are restricted to the upper part of the crust. Two seismic zones are defined by the microseismicity of the Mexicali-Imperial Valley; this activity is mostly clustered in the basement. Typical focal mechanisms are consistent with a strike-slip, right-lateral motion, striking northwest. This is the case for the last four eve ts of ML > 6.0 in the Salton Trough. Focal mechanisms for the seismic zones and the Previous HitheadTop of the Gulf of California are mainly of a strike-slip and dip-slip nature.

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