The Dahuiyeh (Zarand, Iran) Earthquake of 22 February 2005, Ms6.5, A preliminary Field and Seismological Observations

Engineering Seismologist, Seismology Research Center, International, Institute of Earthquake Engineering and Seismology (IIEES), Tehran, Iran, e-mail: mzare@iiees.ac.ir

1. Introduction:

The Dahuiyeh earthquake 22/02/2005, has shocked a seismically active area in SW of Iran in Kerman Province. The region is known by the previous earthquakes occurred in this region; specially the earthquake of 19 December 1977, Mw5.9 (Gisk-Bantangal, North of Zarand) which caused more than 500 life losses and was originated from the reactivation of the Kuhbanan fault (a right-lateral strike slip fault with a length of about 100km). The recent earthquake caused a life loss of more than 600 persons and more than 2000 injured people. Two villages of Dahuiyeh and Hutkan were demolished totally, where the most of the life losses were observed. The damages in the village of Hutkan were corresponded to the location of the village houses in a slop of about 45 degree. On the other hand the damages were amplified in the epicentral region due to a heavy rain and snow fall, which caused heavier roofs, and more suitable conditions for collapse. The maximum intensity of XIII-IX (EMS98) could be assigned to the macroseismic region.

2. Seismotectonic

The recent earthquake of 22/02/2005 was originated evidently from the reactivation of Dahuiyeh fault, a compressional fault that reaches to the Kuhbanan fault at the place of the Dahuiyeh village (Figure-1). The mechanism of the event was compressional (according to Harvard) and compressional with a right-lateral strike slip component (according to NEIC report). The fault plane had a dip towards north. The event was recorded in 12 stations of the IIEES national seismological network. A magnitude of Ms6.5 was estimated for this event according to the record obtained in Maku station with an epicentral distance of about 1400km. The earthquake fault was observed along an previously mapped fault (Dahuiyeh fault) having an east-west trend and making a surface fissure of about 2km length and of vertical displacements from 10 to 30cm. No evident strike slip movement was observed along the surface fissures along the earthquake fault.

3. Damages

The damages due to this earthquake are mostly observed in Dahuiyeh and Hutkan. Most of the life losses are related to Hutkan, where the rural houses were settled in about 45 degree slop. The some of the brick houses, however, seems to survive because of their more resistant and according to their location in the flat part of the village. The macroseismic epicenter was located in a region around Dahuiyeh and the region between Dahuiyeh and Hutkan.

 

 

Figure-1: The quaternary faults of the epicentral region of the 22 February 2005, Dahuiyeh Ms6.5 earthquake.