http://www.meteoweb.eu/2013/09/terremoto-di-magnitudo-5-0-in-eritrea-lungo/226750/
Earthquake of magnitude 5.0 in Eritrea, along the margin of the East African rift
Wednesday, September 18, 2013, 15:46 by Lorenzo Pasqualini
An earthquake of magnitude 5.0 occurred at 11:53 Italian time in Eritrea, about 70 km north-east of the capital Asmara and 18 km from Massawa . The estimated hypocentral depth is 9.8 km. The quake, which to what is the news from Africa has not resulted in damage to persons or property, occurred along the continental margin of the East African rift, the boundary between the African Plate and the Arabian. This is the point where the two plates move away from each other, due to the tectonic extensional. The process of rifting in the course, which is leading to the separation of the two plates, has already led to the formation of an ocean basin: the Red Sea.
The earthquake occurred today just off the coast of the Red Sea, and a few tens of km north of one of the most active volcanic areas in the world. band characterized by extensional tectonics is huge, extending from Turkey to Mozambique for about 6500 km. Its maximum width is recorded at the Red Sea, where it reaches 300 km.
(Software translation)
http://www.decodedscience.com/alaska-ethiopia-earthquakes-week-12-18-september-2013/36958
Continental Breakup: M5.0, Eritrea
Arguably the most interesting earthquake this week is the M5.0 which occurred in Eritrea. Geologically, this area is fascinating: A rising plume of rock sourced from deep within the earth is lifting the crust and will in time initiate continental breakup of Africa, with a new ocean forming between Ethiopia and Sudan.
The M5.0 of 18 September had its epicentre in Eritrea, north of the main hot spot.
This region is known as a triple junction, with ocean ridges along the axes of the Red Sea and Gulf of Aden already splitting Arabia from Africa and creating new ocean crust. The third arm, the East African Rift, propagates southwards to become the Great Rift Valley. With such dynamic processes in action, it’s unsurprising that this area is characterised by extensive volcanism and accompanied by earth tremors, although large earthquakes in the area are rare.
Creative Processes Cause Earthquakes
The Eritrean earthquake, and its association with the Afar mantle plume, is exciting because it reminds us that earthquakes are not merely part of a destructive process – even though most major tremors are associated with subduction and melting of oceanic crust. The constructive processes by which new crust is created also involve enormous crustal forces and, as a result, are capable of generating noteworthy earthquakes.
Sources
United States Geological Survey. Real time earthquake map. Accessed 18 September 2013.
Received on Wed Sep 18 2013 - 13:19:12 EDT