GPS Defines Caribbean Plate in Motion

Researchers: S. Symithe, Purdue University; E. Calais, Ecole Normale Supérieure, Department of Geosciences, PSL Research University; J. B. de Chabalier, Institut de Physique du Globe; and R. Robertson, and M. Higgins, University of the West Indies.

Written by Linda Rowan
30 September 2015

Summary

A plate tectonic model for the Caribbean is derived using most of the available continuous and campaign GPS measurements in the region. The model of present-day motion depicted by the rotation of smaller rigid blocks along locked or partially locked faults shows the rate at which active faults in the Caribbean accumulate strain, an important quantity for seismic hazard assessment. Analysis shows the subduction edge of the Caribbean plate transitions from fully locked near Hispaniola to partially locked under Puerto Rico and the Lesser Antilles. This behavior implies about one magnitude 8 earthquake every 2000 years along the subduction zone.

Observations

The Caribbean plate is a relatively small plate bounded by the North American, South American, and Cocos plates, moving about 2 centimeters per year to the east with respect to North America. This relative motion is accommodated by two nearly parallel east-west-striking strike-slip fault systems along the northern and southern edges of the plate, and by the subduction of the North American plate along its eastern edge.

Determining plate boundary kinematics and deformation in the Caribbean has been difficult because most of the region is under water. Over time, more and more GPS sites have been installed on the many island nations in the Caribbean and throughout the bordering areas of North, Central and South America. After the 2010 Mw 7.0 Haiti earthquake, the U.S. National Science Foundation supported the development of COCONet, a network of geodetic/meteorologic sites throughout the circum-Caribbean to better understand the tectonics and the atmospheric dynamics of this complex region.