M5.8 - PUERTO RICO

Tectonic Summary

The Puerto Rico earthquake of May 16, 2010, occurred in an inclined seismic zone that dips south from the Puerto Rico Trench and that consists of subducted lithosphere of the North America plate. The broad-scale tectonics of the Puerto Rico region are determined by the motion of the Caribbean plate east-northeast at a velocity of about 20 mm/yr with respect to the North America plate. The North America plate is thrust beneath the Caribbean plate at the Puerto Rico Trench, and is seismically active to depths of about 150 km.

Earthquakes, such as this one, that have focal-depths between 70 and 300 km are commonly termed "intermediate-depth" earthquakes. Intermediate-depth earthquakes typically cause less damage on the ground surface above their foci than is the case with similar magnitude shallow-focus earthquakes, but large intermediate-depth earthquakes may be felt at great distance from their epicenters.