A Review of Tectonics and Seismotectonics of Urmia Lake, NW Iran

Abstract

NW of Iran, located in the central portion of the Alpine–Himalayan orogenic belt, has been experiencing active tectonic deformation with a number of damaging earthquakes. In this domain, the tectonic deformation has formed a sizeable Quaternary depression known as Urmia Lake, where a number of active seismogenic fault zones have been identified. There, numerous strong and moderate earthquakes have been recorded. In the last three decades, the seismic sources for some of the events have been identified, with many still remained unknown. In this study, we have presented the results of our neotectonic studies in the region of the Urmia Lake. The region marks by scattered historical earthquakes and recent microseismicity, especially within the northern and southwestern perimeters of the lake. The north front of the lake is bounded by the western termination of the Tabriz ESE-striking fault system. Our studies highlighted at least three active fault zones of Azarshahr, Urmia, and Zarrinehrud in eastern, western, and southern parts of the lake, respectively. It is thought that the formation and evolution of the Urmia Basin have been largely influenced by the tectonic deformation of these fault zones and earthquakes occurrence reveals then its actual evolution. All these faults are more or less NNW-striking oblique-slip (dextral-reverse) Pliocene-Quaternary structural zones. Based on their extended active structural zones, the faults can produce moderate-strong seismic events. According to the recently active fault mapping, it is necessary to update the previous seismic hazard maps of this populous and industrialized region.KeywordsActive faultingUrmia intermountain basinAzarshahr faultUrmia faultZarrinehrud faultNW Iran