Subduction in the Western Makran: the historian's contribution

Abstract

Abstract: The Makran subduction zone, which runs along the southeastern coast of Iran and the southern coast of Pakistan, is a major control on the seismic hazard of the region. Whereas the eastern part of this zone has been active in recent historical times, the western part has not. This could indicate a zone currently locked, or it could be that subduction is occurring aseismically or not at all. Evidence for large thrust activity rests on one event, apparently very large, in 1483. Historical research, especially taking into consideration the political situation in the region at the end of the 15th century, suggests that this 1483 event was a moderate magnitude earthquake in the vicinity of Qeshm Island that has been misassociated with a second, later, earthquake. This interpretation removes from the earthquake catalogue any evidence for major earthquake activity along the Western Makran, and adds weight to the tectonic interpretation that major seismicity has a westerly termination at the Sonne Fault. This presents an interesting example of how a piece of obscure historical information has a significant effect on resolving a question of tectonic interpretation, and with it, influences the estimation of regional seismic hazard, including tsumani hazard in the Indian Ocean.