Estudio comparativo de las fuentes de los temblores de Victoria, junio 9, 1980, del Valle Imperial, octubre 15,1979 y de El Golfo, agosto 7, 1966

Abstract

We study the source of three major earlhquakes lhat occurred in the Salton Trough: The Victoria earthquake (Ms = 6.4) of June 9, 1980, lhe Imperial Valley earthquake (Ms = 6.9) of O~tober 15, 1979, and the El Golfo earthquake (Ms = 6.3) of August 7, 1966. Focal parameters of the first event are estimated by a systematic search in the solution space. For all three earlhquakes, a deconvolution technique was applied to long-period seismograms in order to determine the imesource functions. Furlhermore, a melhod of relative location was utilized for determining the place of the initial and final rupture points. The Victoria earthquake had an unilateral rupture along lhe NW of lhe Cerro Prieto fault; estimates of lhe lenglh and velocity of rupture are 29 km and 2.7 km/sec, respectively. For lhe Imperial Valley earthquake, we obtain a bilateral rupture along the Imperial fault. An unilateral rupture along the NW of lhe Cerro Prieto fault was inferred for lhe El Golfo earthquake; the length and velocity of rupture was estimated in 16 km and 1.9 km/sec, respectively. The time-source function of these three earthquakes show different degrees of complexity. The Imperial Valley and Victoria events appear to be more complex than the El Golfo e arlhquake. Finally, the results of this study show the existence of various secondary pulses; lhey are likely due to structure complexities in lhe source region.