Foundation, Concrete and Earthquake Engineering

Tectonic Process of Magnitude 7.4 Earthquake of Oaxaca, Mexico, 2012 March 20

A magnitude 7.4 earthquake trembled mexico on Tuesday, march 20, 2012 at 12:02:48 PM at epicenter. The location is 16.662°N, 98.188°W at Oaxaca, Mexico. At 20 km depth the earthquake begun to rupture. Historically, there have been several significant earthquakes along the southern coast of Mexico. In 1932, a magnitude 8.4 thrust earthquake struck in the region of Jalisco, several hundred kilometers to the northwest of today's event. On October 9, 1995 a magnitude 8.0 earthquake struck in the Colima-Jalisco region, killing at least 49 people and leaving 1,000 homeless.

The  deadliest nearby earthquake occurred in the Michoacan region 470 km to the northwest of today's event, on September 19, 1985. This magnitude 8.0 earthquake killed at least 9,500 people, injured about 30,000, and left 100,000 people homeless. More recently, a 2003 magnitude 7.6 Colima, Mexico earthquake 640 km to the northwest of today's event killed 29 people, destroyed more than 2,000 homes and left more than 10,000 homeless. The tectonic processes that generate earthquake are:
Tectonic Setting of Magnitude 7.4 Earthquake of Oaxaca, Mexico, 2012 March 20
Tectonic Process
The March 20, 2012 earthquake occurred as a result of thrust-faulting on or near the plate boundary interface between the Cocos and North America plates. The focal mechanism and depth of the earthquake are consistent with its occurrence on the subduction zone interface between these plates, approximately 100 km northeast of the Middle America Trench, where the Cocos plate begins its descent into the mantle beneath Mexico. In the region of this earthquake, the Cocos plate moves approximately northeastwards at a rate of 60 mm/yr.

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