Poster of the Western Guatemala Earthquake of 07 September 2013 - Magnitude 6.5

Tectonic Summary

The September 7, 2013 M 6.6 earthquake near the west coast of Guatemala in the Middle America subduction zone occurred close to the interface between the Cocos and North America plates. The depth and style of faulting of the earthquake indicates slip likely occurred on a very shallow, or near-vertical thrust fault consistent with intraplate faulting within the subducting Cocos plate, rather than on the overlying thrust interface. At the latitude of this event, the Cocos plate moves towards the north-northeast with respect to the North American plate at a rate of approximately 78 mm/yr. The broad scale tectonics of the western and southwestern coast of Central America are dominated by the northeastward subduction of the Cocos oceanic plate beneath the North America plate. Thrust- and normal-type earthquakes are a common occurrence along this plate boundary and the Guatemala region, with events occurring both within the subduction zone - on the megathrust interface and within the subducting plate - and also in the overriding plate. Over the past 40 years, 27 events of M 6.0 or greater have occurred within 300 km of the September 2013 event. Events of note in this region include earthquakes on November 2012 (M 7.4) offshore of Guatemala, which caused around 40 fatalities; September 1993 (M 7.2) offshore of Chiapas, Mexico, which killed one person; and December 1983 (M 7.0) offshore of Guatemala. Other early 20th century earthquakes in the Guatemala region include the August 1942 M 7.9 event, which caused around 40 fatalities, and the April 1902 M 7.5 earthquake, which killed more than 5000 people.

Earthquake Report

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