Preliminary short report of

 Mohammadabad-e-Rigan, Dec. 20, 2010 Earthquake, SE-Iran

Sayyed Keivan Hosseini  &  Hossein Sadeghi

Earthquake Research Center, Ferdowsi University of Mashhad – Iran

2010.12.26

An earthquake with moment magnitude 6.3, hit south east Iran at 28.35 degrees North Latitude and 59.24 degrees East Longitude( 50 km southeast of Mohammadabad-e-Rigan and 120 km SE of Bam in Kerman province)  at 22:12 local time (18:42 GMT) [International Institute of Earthquake Engineering and Seismology (IIEES)] (Figs.1 & 2).

The epicenter of the main shock is located in the vicinity of southern end of the Lut block where the southern extension of two main right lateral strike-slip faults, Bam and Neh faults, converge to each other (Fig.2a).

Using database of IIEES, we show the spatial distribution of aftershock epicenters (Fig. 2b). By considering the aftershock distribution and focal mechanism of the main shock (Global CMT-USGS), the causative fault of this earthquake could be refer to the activity of Kahurak fault, a southern extension of Neh fault with right lateral strike-slip mechanism. Time distribution of aftershock sequences from northeast to southwest may reveal the starting of the main shock rupture from northeast of the causative fault and with directivity toward southwest. Regardless of not suitable distribution of strong motion stations operated by Iran Strong Motion Network (ISMN) in this area, it seems that the northeast stations have not triggered (Fig. 3), which may confirm the directivity toward southwest. Also it seems that the southern part of Bam fault might be triggered too. However, more investigation needed to be done.

Figure 1 :  A map showing the location of Mohammadabad-e-Rigan in Bam section of Kerman province. modified from (http://geography.kermanedu.ir/maps_Kerman.htm)

Figure 2 :  Mohammadabad-e-Rigan Earthquake (Mw 6.3) in SE-Iran. a) (Left)- Topography  map with major faults  and

 the location of main shock epicenter  b) (Right)- Focal mechanism of main shock (Global CMT-USGS) and spatial

 distribution of aftershocks (See text). For plotting all epicenters we have used the database of IIEES and GMT software.

Figure 3 : A map showing the location of strong motion stations (rectangles) and different position of the main shock epicenters

 (red stars) which are located by different institutes. Blue rectangles represent the triggered stations. This figure is belong to http://www.bhrc.ac.ir

Last update: 2010.12.29   local time: 16:30