The United States Geological Survey recorded a Magnitude 4.2 Earthquake at a depth of 10.1 km beneath southern Chihuahua State, Mexico, roughly 115 km to the southeast of Chihuahua City, slightly after 1.40 am local time (slightly after 7.40 am GMT) on Friday 13 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 13 September 2013 Chihuahua Earthquake. Google Maps.
Mexico has two major tectonic boundaries. To the east Baja California lies on the Pacific Plate is moving northwest with regard to the North American Plate, while the North American Plate is moving southeast relative to the Pacific Plate. This creates a transform plate margin along the center of the Gulf of California, as the two plates slide past one-another, a margin that continues northward under California as the San Andreas Fault. To the south, along the Middle American Trench, which lies off the southern coast off Mexico, the Cocos Plate is being subducted under the North American Plate, passing under southern Mexico as it sinks into the Earth.
While neither of these plate margins is close to Chihuahua, they do together contribute to a build up of tectonic pressure in the wider area, which occasionally causes Earthquakes as the rocks beneath the surface adjust their position to release this stress.
See also Magnitude 2.8 Earthquake in Baja California, Magnitude 4.7 Earthquake in Guerrero State, southwest Mexico, Magnitude 3.1 Earthquake to the north of the Gulf of California, Magnitude 6.2 Earthquake in southern Mexico and Fresh eruption on Mount Popocatépetl disrupts flights around Mexico City.
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