Seismicity and Tectonics of the Northern Gulf of California Region, Mexico. Preliminary Results

Abstract

Three new seismographic statioms have been established· in the northern Gulf of California region; Mexico. Seismicity ,during a representative period in April and May of 1969 was concentrated on the Imperial, San Jacinto, Sierra Juarez, .and San Miguel faults, and the spread of epicentral locations was m\!Ch less than had previously been indicated. An intense earthquake swarm in March of· 1969 occurred near Consag Rock in the northern Gulf, and its study contributes to our understanding of the regional tectonics. In the northern Gulf of California and adjacent Salton trough, the tectonic framework may be. approximated by a series of six transform faults connected by five spreading centers (ridge, segments) evidenced by geothermal areas, recent .. volcanic activity, earthquake swarms, and submarine topographic depressions. Complexities in the fault pattern may be related to a northward decrease in spreading rates along the ridge segment,s. Five new high; quality seismographic stations around the •Gulf of California are now under construction in order to understand in more detail the pattern of sea-floor spreading in this unique, and important region.