A Magnitude 4.4 Earthquake at a depth of 50.6 km occurred on the Altiplano Plateau in Jujuy Province in the northwest of Argentina slightly before 9.10 pm local time on Thursday 5 September 2013 (slightly before 0.10 am on Friday 6 September GMT), according to the United States Geological Survey. This is not a large quake, and occurred at some depth in a sparsely inhabited region, so it is unlikely to have caused any damage or injuries, but may have been felt locally.
The approximate location of the 5 September 2013 Altiplano Earthquake. Google Maps.
Jujuy Province is located in the Andes Mountains, one of the most tectonically active mountain ranges in the world, and has a history of earthquakes. The Andes are being formed as the Nazca Plate to the west is subducted beneath the South American Plate. This causes quakes in a number of ways. Firstly there is friction between the two plates as the Nazca Plate passes under South America. Then there is crumpling and upthrust of the South American as it is pushed from the west by the Nazca Plate and from the east by the expansion of the Atlantic. Finally there is volcanic activity in the Andes, as lighter minerals in the Nazca Plate are melted by the heat of the Earth's interior, then rise up through the overlying South American Plate to form volcanoes.
See also Deep Magnitude 4.5 Earthquake in northwest Argentina, Evacuations ordered after activity on Copahue, Eruption on Mount Copahue and Earthquake in Jujuy Province, NW Argentina.
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