Crustal Structure and Seismotectonics of Northern Baja California
Published:January 01, 1991
J. Frez, J. J. González, 1991. "Crustal Structure and Seismotectonics of Northern Baja California", The Gulf and Peninsular Province of the Californias, J. Paul Dauphin, Bernd R. T. Simoneit
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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 events of ML > 6.0 in the Salton Trough. Focal mechanisms for the seismic zones and the head of the Gulf of California are mainly of a strike-slip and dip-slip nature.
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The Gulf and Peninsular Province of the Californias
The Gulf of California is an excellent laboratory for studying sedimentary processes on time scales that are not resolvable in the open ocean. The high biological productivity and the unique physical character of the gulf combine to produce sedimentological processes that preserve annual phenomena. This volume is organized into six sections. Part 1 covers historical exploration of the area. Part 2 includes 5 chapters detailing information contained on the 5 fold-out maps that accompany the volume. Part 3 consists of chapters on regional geophysics and geology. Part 4 covers satellite geodesy. Part 5's seven chapters discuss physical oceanograpy, primary productivity, and sedimentology. Part 6 covers hydrothermal processes.