- © 2006 by the Seismological Society of America
On 22 June 2002 a large earthquake struck near the town of Avaj in northwestern Iran (figure 1). The earthquake completely destroyed seven villages and severely damaged more than 80 villages; it was felt to distances of 100 km. According to official reports, more than 260 people were killed and 1,300 were wounded. The magnitude of the earthquake was determined to be mb = 6.0 by the Geophysical Institute of Tehran University (GITU), Ms = 6.0 by the National Earthquake Information Center (NEIC), and Mw = 6.5 by the U.S. Geological Survey (USGS; http://www.usgs.gov). The focal depth of the event, according to the USGS report, was approximately 10 km. The mainshock was recorded by 50 accelerograph stations. At a station in Avaj, 28 km from the epicenter, the maximum horizontal and vertical accelerations were recorded at approximately 0.5 g and 0.26 g, respectively.
Avaj is a small town, 107 km southwest of Qazvin city. Avaj and the surrounding regions are agricultural areas; most of the people living in this area are farmers. Most of the houses in the epicentral region were single-story masonry buildings, many of them old and very weak. Virtually all of the buildings of this type collapsed completely during the earthquake. Buildings that had been built according to the Iranian code of practice for seismic-resistant design performed much better.
SEISMOTECTONICS AND SEISMICITY OF THE REGION
From a seismotectonic point of view, Avaj is located in the central part of an active zone that includes several major faults: the Soltanieh fault, the North Zanjan fault, the Ipak fault, the Kushk-e-Nosrat fault, etc. (figure 2). The general direction of fault trends in the region is N40°–50°W. These faults have been active in the past, especially during the …