Sunday 29 September 2013

Magnitude 4.2 Earthquake in Semnan Province, northern Iran.

The United States Geological Survey recorded a Magnitude 4.2 Earthquake at a depth of 12.9 km in western Semnan Province, northern Iran, slightly before 9.35 am local time (slightly before 6.05 am GMT) on Friday 27 September 2013. There are no reports of any damage or casualties arising from this quake, although it is likely to have been felt locally.

The approximate location of the 27 September 2013. 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.

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