Sunday, 23 July 2017

Magnitude 6.7 Earthquake between Kos and the Bodrum Peninsula kills two.

The United States Geological Survey reported a Magnitude 6.7 Earthquake at a depth of 10 km between the Greek island of Kos and the Bodrum Peninsula, Turkey, slightly after 1.30 am local time on Friday 21 July 2017 (slightly after 10.30 pm on Thursday 20 July, GMT). Two people have been reported dead on Kos following the event, both of whom have been identified as tourists, one being from Sweden and the other from Turkey, though they have not yet been named. About 430 people have been injured on Kos and Bodrum, with both having suffered extensive damage to buildings and infrastructure,and many tourists trapped in the area. A small tsunami was reported on Kos, and people have reported feeling the event as far away as Crete.

Damaged buildings on Kos following the 21 July 2017 Earthquake. Louisa Gouliamaki/Getty Images.

The island of Kos lies on the boundary between the Anatolian Plate, to the north, the Aegean Sea Plate (underlying the Peloponnese, Attica, The Cyclades Islands, Crete, the Dodecanese Islands and Turkey to the southeast of the Taurus Mountains) to the west and the African Plate to the south. Northern Greece and the north coast of Turkey lie on the Eurasian Plate. Both countries are highly prone to earthquakes because of this.

 The approximate location of the 21 July 2017 Kos Earthquake. USGS.

To the east the Arabian Plate  is being pushed north and west by the movement of the African Plate, further to the south. This leads to a zone of tectonic activity within the province, as the Arabian and Anatolian plates are pushed together, along the East Anatolian Fault, and past one-another, along the Dead Sea Transform.

 Damaged buildings on Kos following the 21 July 2017 Earthquake. Sky News.

This movement also leads to a zone of faulting along the northern part of Turkey, the North Anatolian Fault Zone, as the Anatolian Plate is pushed past the Eurasian Plate, which underlies the Black Sea and Crimean Peninsula  (transform faulting). This is not a simple process, as the two plates constantly stick together, then break apart as the pressure builds up, leading to Earthquakes, which can be some distance from the actual fault zone.

 Damage to boats at Bodrum following the 21 July 2017 Earthquake. Anadolu Agency.

The Aegean Sea Plate is moving southwest with regard to the Eurasian and Anatolian Plates, and being subducted beneath the African Plate to the south. Its margin with the Eurasian Plate is a divergent and a transform margin at different points. This is not a smooth process, with rocks tending to stick together, then being forced to move as the pressure builds up, typically in stops and starts that lead to Earthquakes.

 Simplified map of the plate movements of the eastern Mediterranean. Univeriteit Utrecht.

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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