The 16 April 2013 Mw7.8 Ghosht, Iran earthquake

On Tuesday 16 April 2013 at 10:44:22 UTC, a strong Mw = 7.8 earthquake shook not only Iran but also southwestern cities of Asia and southern Persian Gulf countries. This event occurred in a sparsely populated mountain and range region near a small town called Ghosht (located in Iran) but left destructions and causalities around the city of Mashkel in Pakistan. It was followed by a medium sized Mw = 5.7 aftershock on 17 April 2013 without any reported destructions or causalities. The regional tectonics is under the influence of multiple convergences between the Persian Gulf plate, Indian and Eurasian plates. We applied deviatoric inversion to search for the best-fitted moment tensor and dislocation grid search to illustrate the best source mechanism by grid search over double couple fault plane parameters. Deviatoric inversion found 39% of CLVD for the mainshock and 5% of CLVD for its following aftershock. This CLVD component may be related to that zone of the subduction where the sinking slab is down going under its density and cause normal mechanism. The best-fitted double couple after dislocation grid search estimated: strike 75, dip 35, rake −75 (all in degree) and Mw = 7.66, for the mainshock and strike 80, dip 40, rake −90 (all in degree) and Mw = 5.53 for its aftershock. According to seismicity distribution there exist two types of seismicity: (1) crustal seismic activity band near Makran coasts (above 50 km depth) and (2) under crustal band (between 50 km and 150 km) plus a gap of seismicity between Makran and the rest of the Persian Plateau.