Sassan Eshghi; PhD (s.eshghi@iiees.ac.ir)
Mehdi Zare; PhD (mzare@iiees.ac.ir)
Mohammad R. Mahdavifar; MSc (mahdavif@iiees.ac.ir)
1. Introduction
The Changureh (Avaj) earthquake of June 22, 2002 (7:28:00 a.m. local
time, 2:58:27.2 GMT) has shocked the NW Iran (about 250km west of Tehran;
Fig.1). The region is located in the west of Takestan-Hamedan road along
an east-west oriented valley in the west of the Abegarm village.
The localities of the greatest damages are the villages of Abdarreh and
Changureh (Fig.1). The most recent report on life losses says about 261
death person and 1300 injured people. The earthquake impressed generally
about 50 villages (most of them partially damaged). The macroseismic
intensity of VII-VIII (in EMS-98 scale) could be assigned to the
mentioned villages in the epicentral area.
2. General Tectonic Setting
The structural trends in this region are formed based on the east-west
trend fault lines (along the Ipak fault which arrives to the Abegarm village),
and the NW-SE fault lines in form of northern Central-Iran. The Ipak fault
has interrupted the Avaj valley in the north of Abegarm (just in the eastern
parts of the meizoseismal zone). The earthquake has evidently happened
along the major WNW-ESE trend of an apparently hidden fault. The surface
east-west fissures are observed in the north of Changureh caused
by the 22 June 2002 earthquake.
The surface fissures could be related to the compressional mechanism;
Fig.2 (as it is supported by the estimated focal mechanism reports
coming from the international seismological organizations). The trend of
the major damaged area is in the western continuation of the Ipak fault
that terminates in the general region of Abegarm. The elongation of the
meizoseismal trends gives as well a general near east-west trend.
3. The Extent of Damage
The structural damage to rural buildings were extended in a region
mainly between Avaj in the south and Abegarm in east and Shirinsoo in the
west and Abhar in the north. Most of the buildings were single
storey and made up of adobe (Fig. 3) and masonry(Fig.
4) materials. They were mostly non-engineered structures and
could not withstand seismic forces. The structural failure
and collapse resulted from wall to wall separation, lack of
structural integrity, lack of proper lateral resisting system and
non-ductile materials. Structural collapse was widespread in Changureh
and Abdarreh.
Electrical local network was disrupted and it was partially
restored after 8 hours (Fig. 5). Water and irrigation systems were
damaged severely in the meizoseismal zone. A simple span
bridge near Changureh village was partially damaged (Fig. 6).
Fig. 1
Fig. 6