The Dahuiyeh (Zarand) earthquake of 2005 February 22 in central Iran: reactivation of an intramountain reverse fault

Abstract

S U M M A R YWe used seismic body waves, radar interferometry and field investigation to examine the source processes of the destructive earthquake of 2005 February 22 near Zarand, in south-central Iran. The earthquake ruptured an intramountain reverse fault, striking E-W and dipping north at ∼60• to a depth of about 10 km. It produced a series of coseismic scarps with up to 1 m vertical displacement over a total distance of ∼13 km, continuous for 7 km. The line of the coseismic ruptures followed a known geological fault of unknown, but probably pre-Late Cenozoic, age and involved bedding-plane slip where the scarps were continuous at the surface. However, any signs of earlier coseismic ruptures along this fault had been obliterated by the time of the 2005 earthquake, probably by land sliding and weathering, so that the fault could not reasonably have been identified as active beforehand. The 2005 fault is at an oblique angle to the rangebounding Kuh Banan strike-slip fault, and may represent a splay from that fault, related to its southern termination. Other intramountain reverse faulting earthquakes have occurred in Iran, but this is the first to have produced a clear, mapped surface rupture, and to have been studied with InSAR. Faults of this type represent a serious seismic hazard in Iran and are difficult to assess, because their geomorphological expression is much less clear than the range-bounding reverse faults, which are more common and have been better studied.

Active faulting within a megacity: the geometry and slip rate of the Pardisan thrust in central Tehran, Iran

“…Studies of recent Iranian earthquakes have demonstrated that many have occurred on previously unrecognized active faults (e.g. Talebian et al 2004Talebian et al , 2006. In urban areas, the identification and characterization of active faults is further limited by human activity, and yet the combined use of historical aerial imagery and modern satellite-derived digital topography data can help to overcome those challenges.…”

Offset rivers, drainage spacing and the record of strike-slip faulting: The Kuh Banan Fault, Iran

“…The Kuh Banan Fault is seismically active Talebian et al, 2006). Numerous earthquakes have been recorded (Fig.…”

“…1b), including the M s 5.8 Bob-Tangol earthquake at 30.9ºN 56.6ºE on 19 th December 1977 and other large events in 1933 and 1978 on the northern section of the fault. Earthquakes have also occurred on nearby faults, including the Dahuiyeh thrust which ruptured in 2005 (Talebian et al, 2006) and the Behabad fault .…”

Megathrust and accretionary wedge properties and behaviour in the Makran subduction zone

“…Where available, we use published earthquake depths and mechanisms from this technique (Laane and Chen, 1989;Byrne et al, 1992;Baker, 1993;Berberian et al, 2000;Maggi et al, 2000;Berberian et al, 2001;Jackson et al, 2006;Talebian et al, 2006;Engdahl et al, 2006;Nissen et al, 2010Nissen et al, , 2011Walker et al, 2013;Barnhart et al, 2014b;Jolivet et al, 2014;Penney et al, 2015). In addition, we have used teleseismic P and SH bodywaveform modelling to determine the depths and focal mechanisms of 7 earthquakes for which solutions have not previously been published.…”