Monday 21 October 2013

Magnitude 4.7 Earthquake in southern Balochistan.

The United States Geological Survey recorded a Magnitude 4.7 Earthquake at a depth of 15.6 km in southern Balochistan Province, southwest Pakistan, slightly after 6.10 pm local time (slightly after 1.10 pm GMT) on Friday 18 October 2013. There are no reports of any damage or injuries arising from this quake, though it was felt across much of the province, and caused brief outbreaks of panic in several areas.

The approximate location of the 18 October 2013 Balochistan Earthquake. Google Maps.

The geology of Balochistan is dominated by the Makran Fault System, or Makran Accretionary Wedge. The Arabian Plate is being subducted along the Makran Subduction Zone to the south of Balochistan, passing under the province, which sits on the southern Eurasian Plate, as it sinks into the Earth. The two plates do not move past one another smoothly, but continuously break apart and then stick together until the pressure builds up sufficiently to cause another break, leading to Earthquakes in the process. In addition to this the Eurasian Plate is scraping sedimentary material off the leading edge of the Arabian Plate as it is subducted, forming an accretionary prism of material over the subduction zone up to 7.5 km think in places. This takes the form of a series of parallel folded hill ranges running east to west across the province and Sistan & Baluchistan Province in neighbouring Iran.

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