Sunday, 24 November 2013

Two Earthquakes in southern Iran.

The United States Geological Survey recorded a Magnitude 4.9 Earthquake at a depth of 44 km roughly 25 km to the southeast of the city of Khvomuj in southern Bushehr Province, Iran, slightly after 12.35 pm local time (slightly after 9.05 am GMT) on Tuesday 19 November 2013. This was followed by a second quake with a Magnitude of 4.6 at a depth of 27.4 km, 10 km to the northwest of the city of Arad in Fars Province, slightly after 5.00 pm local time (slightly after 1.30 pm GMT) on the same day. These are moderately large quakes, and are likely to have been felt across a wide area, though there are no reports of any damage or casualties.

The locations of the two 19 November 2013 southern Iran Earthquakes. The Bushehr Province quake is purple and the Fars Province quake is red. Google Maps.

Iran is situated on the southern margin of the Eurasian Plate. Immediately to the south lies the Arabian Plate, which is being pushed northward by the impact of Africa from the south. This has created a zone of faulting and fold mountains along the southwest coast of the country, known as the Zagros Thrust Belt, while to the northeast of this the geology is dominated by three large tectonic blocks, the Central Iran, Lut and Helmand, which move separately in response to pressure from the south, stretching and compressing the rock layers close to the surface and creating frequent Earthquakes, some of which can be very large.

The population of Iran is particularly at risk from Earthquakes as, unlike other Earthquake-prone nations, very few buildings in the country are quake-resistant. The majority of residential buildings in Iran are made of mud-brick, a building material particularly vulnerable to Earthquakes as the bricks often liquify, trapping people inside and quickly asphyxiating them with dust. This is particularly dangerous at night when the majority of people are inside sleeping, but it is to be hoped that this quake, which occurred in the late afternoon has caused less casualties than some historic nighttime quakes.


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