Thursday 9 February 2017

Magnitude 6.3 Earthquake on the coast of Balochistan Province, Pakistan.

The United States Geological Survey recorded a Magnitude 6.3 Earthquake at a depth of 25.9 km, roughly 20 km to the southwest of the city of Pasni in Balochistan Province, Pakistan, slightly after 3.00 am local time on Tuesday 7 February 2017 (slightly after 10.00 pm on Monday 8 February GMT). An event of this size is potentially very dangerous, and there were initial concerns that this event might lead to a large number of casualties, however there have only been reports of minor damage in this instance.

Damage in Pasni, Balochistan, following the 7 February 2017 Earthquake. AFP.

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.
 Plate boundaries and movements beneath southern Pakistan, Iran and the Arabian Sea. University of Southampton.
Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.
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