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 indicated
the slip likely occurred on a very shallow, or near-vertical thrust faults consistent with
intraplate faulting within the subducting Cocos plate, rather than on the overlying
At the latitude of this event, the Cocos plate moves towards the north-northeast with
respect to the North American plate at the 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.