Tectonic Summary

The October 9, 2014 M 7.1 earthquake near the Southern East Pacific Rise occurred as the result of oblique thrust faulting in the complex plate boundary region at the intersection of the Pacific, Nazca and Antarctic plates, nearly 600 km to the south of Easter Island. At the location of the earthquake, some 100 km to the east of the East Pacific Rise, the Nazca plate diverges from the Pacific at a rate of nearly 15 cm/yr, in a direction slightly south of due east. Some authors identify a small microplate in this region, called the Juan Fernandez plate; the October 9 earthquake occurred near the northern boundary of this tectonic block with the broader Nazca plate.

Moderate sized earthquakes are not uncommon in this region of the East Pacific Rise, though events of this size are rare. Fifteen other M 6+ earthquakes have occurred within 500 km of the 2014 event over the past century – until today none had been larger than a M 7.0 in March 1920, 400 km due south of the October 9, 2014 earthquake. Because of the remote location away from any land, none of these events are known to have caused damage. The M 7.1 2014 event was followed by an M 6.6 aftershock 18 minutes later.