M 7.2 - 42 km NNW of Carahue, Chile

Tectonic Summary

The January 2, 2011, M 7.2 Araucania, Chile earthquake occurred as the result of shallow thrust faulting on or near the subduction interface between the Nazca and South America tectonic plates. At the location of this event, the Nazca plate moves east-northeast relative to South America at a velocity of about 74 mm/yr. The Nazca plate, oceanic in origin, subducts eastward beneath the South America plate at a shallow angle from the Peru-Chile Trench. It is seismically active to depths of approximately 200 km adjacent to the epicenter of the January 2nd earthquake, though farther north seismicity continues to depths exceeding 600 km.

The January 2nd earthquake occurred at the southern end of the aftershock region of the damaging M 8.8 Maule megathrust earthquake of February 27, 2010, and can also be considered an aftershock of that event. The subduction zone between the Nazca and South America plates has a long history of large megathrust earthquakes, including the largest event ever recorded, a M 9.5 event in 1960, which ruptured a fault mostly to the south of the January 2nd earthquake.

Hayes et al. (2016) Tectonic summaries of magnitude 7 and greater earthquakes from 2000 to 2015, USGS Open-File Report 2016-1192. (5.2 MB PDF)