Seismicity and tectonics of the northern Gulf of California region, Mexico. preliminar y results

Abstract

Three new seismographic stations 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 Juárez, and San Miguel faults, and the spread of epicentral locations was much 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 tectonie framework may be approximated by a series of six transform faults connected by five spreading centers (ridge segments) evideced by geothermal arcas, 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 segments. 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 seaf loor spreading in this unique and important region.