Mechanism of the main shock and the aftershock study of the Tabas-e-Golshan (Iran) earthquake of September 16, 1978: A preliminary report

Abstract

abstract Aftershocks of the Tabas-e-Golshan earthquake (Ms = 7.7) of September 16, 1978 were recorded with a local network of portable seismometers. The main shock produced a discontinuous series of surface ruptures extending 85 km NNW and dipping ENE beneath the Shotori Range. The largest aftershocks located thus far are not concentrated in the hypocentral region of the main shock nor near the ends of the rupture zone but appear to be concentrated down-dip from gaps in the surface ruptures. This suggests that these features may extend to depth and act as barrier zones in the rupture process. The 65 km long zone of aftershock activity dips 40°ENE from the surface break, which agrees with the focal mechanism for the main shock in indicating thrusting on a NNW-striking, ENE-dipping fault. The aftershocks range in depth from 2 to 24 km with greatest concentration in the depth range 5 to 10 km.