Monday 24 December 2012

Earthquake beneath the eastern Black Sea.

On Sunday 23 December 2012, slightly after 5.30 pm local time (slightly after 1.30 pm GMT) the United States Geological Survey recorded a Magnitude 5.5 Earthquake 10 km beneath the eastern Black Sea, roughly 35 km off the coast of Georgia. This is a fairly large quake for the area, but this far offshore is unlikely to have caused any damage or casualties. The quake was felt in Georgia, Turkey and Russia.

The location of the 23 December Earthquake. Google Maps.

The Black Sea is largely upon the Eurasian Plate, as are Georgia and Russia. Turkey, however, lies on a separate plate, the Anatolian Plate. This is being pushed to the west by the northward movement of the Arabian Plate, which is in turn being pushed by the African Plate, further to the south. This creates as zone of faulting along the northern part of Turkey, the North Anatolian Fault Zone, as the two plates are pushed past one-another (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.

How the movement of the Arabian Plate causes movement on the North Anatolian Fault Zone. Université Montpellier 2.

This northward movement of the African and Arabian Plates also causes folding and uplift in the Caucasus Mountains, which separate Georgia from Russia. Again this is not a smooth process, with the rocks sticking together, then moving sharply as the pressure builds up enough to break them appart, which can also lead to Earthquakes in the region.

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