Changureh (Avaj) Earthquake of 22 June 2002, Mw=6.3
The Changureh (Avaj) earthquake of 22 June 2002, Mw=6.3 (7:28:00 a.m. local time, 2:58:27.2 GMT) was strongly felt in most parts of NW Iran. The epicenter, about 250 km west of Tehran and west of the Takestan-Hamedan road, is located within an roughly east-west oriented valley just west of the Abegarm village. The greatest damages occurred in the villages Abdarreh and Changureh. Reports lists 261 fatalities, about 1300 injured and more than 50000 homeless people. The earthquake affected about 50 villages (most of them partially damaged). The macroseismic intensity of VIII+ (EMS-98 scale) could be assigned to Abdarreh and Changureh in the epicentral area. Based on the extent of the surface fissures and an estimated focal depth of 7 km, a magnitude of Mw = 6.3 has been estimated for the event. The preliminary process of source parameter estimates indicates a high stress drop and fast ground motion attenuation. The Changureh earthquake area is characterized by the dominant NW-SE and WNW-ESE directed fault systems. The area includes the major NW-SE and east-west structural trends in the southwestern Alborz region and north-central Iran. There are, hence, major intersections of active tectonic structures that generated great earthquakes already in the past (1177 and 1962 Buin-Zahra earthquakes with estimated magnitudes > 7.0). However, the region of northern Avaj has been seismically less active in historic times (according to the historical and 20th century earthquake catalog). The recent 22 June 2002 earthquake is a major event that seismically illuminated the western continuation of the Divandarreh-Buin lineament. The focal mechanism of the event, representing mostly compressional deformation, agrees with the field observations. Some surface fissures observed in the region around Changureh are uncontinuously along about 3 km (for example in the road beteen Abdarreh and Changureh). Some other surface fissures have been reported between Changureh and Avaj in a direction from Changureh towards Abegarm. These fissures had the general strike of N70-80W. The length along which the surface fissures have been reported was about 20 km. Some tension cracks were observed as well with N5-20W directions perpendicular to the compressional features.
