M 7.2 - 46 km WSW of Dalbandin, Pakistan

Tectonic Summary

The January 18, 2011, M 7.2 earthquake of southwestern Pakistan occurred as a result of shallow normal faulting within the lithosphere of the subducted Arabia plate. Focal mechanism solutions indicate that rupture occurred on either a steeply dipping normal fault striking southwest, or on a moderately dipping normal fault striking east-northeast. Slip on a fault aligned with either nodal plane is consistent with the intraplate setting of this event.

The present-day tectonic environment of Pakistan is determined by the motions of the Arabia and India plates north-northeast with respect to the Eurasia plate at velocities of 35–40 mm/yr at the location of this earthquake. Arabia plate lithosphere is subducted beneath the Eurasia plate at the Makran Coast of Pakistan and Iran and becomes progressively deeper to the north. The subducted Arabia plate is seismically active to depths of about 160 km. The frequency of moderate and large earthquakes within the subducted Arabia plate is not high compared with the frequency of such events in some other subducted plates worldwide, but several earthquakes have occurred within this slab in the region of the January 18th event over the past 30 years, including a M 7 event 200 km to the southwest in April 1983 that resulted in no recorded casualties or damage.

Hayes et al. (2016) Tectonic summaries of magnitude 7 and greater earthquakes from 2000 to 2015, USGS Open-File Report 2016-1192. (5.2 MB PDF)