August 08, 2010, Sheikhupura, Pakistan earthquake: seismotectonic investigation using focal mechanism solution and gravity data

Abstract

A shallow-focus (3.8 km deep) and low-magnitude (ML 3.8) earthquake occurred near Sheikhupura on August 08, 2010. Shaking was felt in parts of Potwar and northern Punjab but no associated damage has been reported. Tectonically, this earthquake occurred to the south of the Salt Range in the Punjab Seismic Zone (PSZ), a shallow-focus, moderate-level seismic zone characterized by steeply dipping strike-slip and extensional faults. The focal mechanism solution, using the seismological data of the United States Geological Survey and local observatory, shows an EW-trending fault plane dipping 710 N similar to the normal faults reported in the area previously. On the basis of the imposition of the stress field on the northward-moving Indian plate and the nature of the FMS of the previous and this earthquake, the Sheikhupura earthquake is considered as one of the intraplate earthquakes occurring frequently in the PSZ. The location of the event on the Bouguer gravity maps coincides with the zone of high gravity anomaly reflecting igneous intrusion(s) or, more likely, structural disturbances (i.e., extensional faulting in the basement).