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Author Name: B. Oveisi & M. Eskandari
Publisher Date : September 2010
Group Name : Seismotectonic & Seismology
Title : KONARTAKHTEH earthquake (27 Sep 2010 ) 1
Description :
The 2010 Sep 27 Konartakhteh Fars earthquake (M 6.1 IRSC, Mw 5.6 USGS) shook central Zagros, close to the active Kazerun Fault.
Full Description:

 

Preliminary report on KONARTAKHTEH earthquake Mw 5.7 Sep 27th 2010, Central Zagros-Iran 

B. Oveisi & M. Eskandari

The 2010 Sep 27 Konartakhteh Fars earthquake (M 6.1 IRSC, Mw 5.6 USGS) shook central Zagros, close to the active Kazerun Fault. The earthquakes affected hundreds of square kilometers. Our preliminary results based on a iso-seismal model show that the maximum intensity zone (MSK VIII or more, a>100 gal, Konartakhteh) should be located close to the epicenter, where the anticlinal structure drug horizontally due to the mechanism of right lateral movement along the Kazerun fault. The Kazerun fault is seismically active at the present day, with sesimicity indicating right lateral movement. The fault is clearly visible on the aeromagnetic map of the region as a sharp magnetic lineament. The fault consists of two right-stepping segments: the Kazerun fault to the north and Borazjan fault (considered as a tear segment of the MFF in this thesis) in the south, with a gap in between (Berberian, 1981). It trends N-S fault cross the ZFB causing bending, dragging and offsetting of the fold axes in a right-lateral sense. We suggest that the causative fault should be an ESE-ward embranchment fault.

 

The region to the east of the Kazerun Fault (the Fars region) contains more than 100 Hormuz salt diapirs emerging at the surface. However, this salt formation, which is probably between 1 and 2 km thick, does not exist to the west of the fault zone in the Dezful Embayment, as indicated conclusion is supported by the fact that no Hormuz salt diapirs are found to the west of the Kazerun Fault, even on seismic profiles, and no Hormuz salt has been encountered in any of the hundreds of wells which have been drilled in this region. Authemayou et al. (2005) suggest that the KF, as a system of active right-lateral strike-slip faults, has propagated southwestward from the MRF toward the main Arabian indenter due to anticlockwise rotation of Arabia. They propose an important role for the KF and associated faults in transmitting and distributing of partitioned strike-slip motion of oblique plate covergence. Based upon GPS measurements, Walpersdorf et. al. (2006) have estimated 6±2 mm/year present-day displacement rates (maximum value inferred across the whole Kazerun strike-slip fault system).  Using inferred fault geometry based on structural data adjacent south of the Konartakhte (Gisakan fold) allows efficiently estimating horizontal shortening from tectonic uplift recorded by fluvial terraces (Oveisi et al., 2008). Shortening rate estimated 2.9±0.3 across the Gisakan fold, when assuming a uniform and parallel uplift of river terraces and a MFF ramp dipping at a 39±3°.  The principal strainrates 25 ppm deduced form GPS observations (Tavakoli et al., 2007).

Preliminary report on KONARTAKHTEH earthquake Mw 5.7 Sep 27th 2010, Central Zagros-Iran

 

 


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