Preliminary report of December 23 2012 Khoy Earthquake, NW Iran

Description

Preliminary report of December 23 2012 Khoy Earthquake, NW Iran Shahryar SOLAYMANI AZAD, Massoumeh Eskandari, Mohammad Ali Shokri Seismotectonic and Seismology Department (SSD), Geological survey of Iran The Khoy seismic event of December 23 2012 (M= 4.8: IRSC, M= 5.2: USGS) occurred at 06:38:58 UTC (10:08:58 local time on 3 Dai 1391) within west Azerbaijan province, Iran. The instrumental epicenter of the event given by IRSC is 38.50° N, 44.95° E; located at the south vicinity of Khoy city with 12.0 km in depth (IRSC) (Figure 1, Table 1). Figure 1: Epicenter of December 23 2012 Khoy earthquake (ML= 4.8) from IRSC (crossed rectangular). The seismic event occurred potentially on Guilato-Siacheshmeh-Khoy fault System. Considering the epicenteral location of the earthquake (e.g. IRSC), it seems that the seismic event could be caused by Guilato-Siahcheshmeh-Khoy fault system. Khoy, Siahcheshmeh and Guilato faults are three major NW-SE fault zones in NW Iran-Transcaucasian territory (e.g. Berberian, 1997; Solaymani Azad, 2009) (Figure 1). The Khoy fault system as the southeastern continuation of Guilato-Siahcheshmeh strike-slip fault zones (mainly dextral), appears in south adjacent of Khoy town and continues to about 70 km NW towards Siahcheshmeh area. In general, the Khoy fault (~70 km length) manifests a discrete shape of fault segments. Both historical seismicity (e.g. 1843 AD) (e.g. Ambraseys and Melville, 1982) and surface morphology of the fault reveal that it is an active fault. The Khoy fault zone is consequently a seismic source which is capable to produce moderate to strong seismic events with vast destructions within Khoy and Siahcheshmeh area.     Table 1: Earthquake characteristics of the December 23 2012, based on deferent references IRSC: Iranian Seismological Center IIEES: International Institute of Earthquake Engineering and Seismology USGS: U.S. Geological Survey EMSC: European-Mediterranean Seismological Center   Focal mechanisms of the seismic event (GFZ, 2012; KAN, 2012) have presented in Figure 2     Figure 2: Two focal mechanisms of the event, presented by GFZ, 2012 and KAN, 2012.