Tectonic Summary The September 7, 2013 (UTC) Guatemala earthquake (Mw6.5) occurred near the west coast of Guatemala in the Middle American trench. The event occurred at or near the interface between the Cocos and North America plates. The style of faulting based on the W-phase source mechanism indicates slip likely occurred on a shallow thrust fault consistent with the subduction 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 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 and in the overriding plate. Over the past 40 years, 27 events of Mw6.0 or greater have occurred within 300km of the September 2013 event. Events of note in this region include earthquakes on November 2012 Mw7.4 offshore of Guatemala, which killed 39 people; September 1993 Mw7.2 offshore of Chiapas, Mexico, which killed one person; and December 1983 Mw7.0 offshore of Guatemala. Other early 20th century earthquakes in the Guatemala region include August 1942 Mw7.9, which killed 38 and April 1902 M7.5, which killed more than 5000 people.
Posted on: Sat, 07 Sep 2013 03:25:41 +0000
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