ACTIVATION OF A MANTLE FAULT BENEATH THE HINDU KUSH IN 1983-1985

Abstract

We earlier used earthquake data to demonstrate that in plates undergoing subduction beneath the Hindu Kush and the Kermadec Islands the depth of occurrence of aseismic 'windows' (belt) varies in a 10- to 11-year cycle, assuming the threshold of seismicity to be M ≥ 5.0 in the first case, and M ≥ 4.5 in the second. It is important to demonstrate that the foci of the main earthquakes and their aftershocks had the same focal mechanism. Thus we observe in both cases a nearly horizontal NW-SE strike of the compression axis, typical of the entire Central Asian region; and subzonal and northwestward strikes of the possible separation planes, with thrust movements taking place along them. To elucidate the significance of these earthquakes, we consider their spatial distribution and examine it together with the temporal component shown.