One Island, Two Faults Adds Up to Trouble Ahead

Haiti's devastating earthquake came as a shock to most non-geologists, but the Caribbean is one of the most seismically active areas in the world. The Caribbean plate is squeezed between two larger plates, the North American and South American, creating loaded fault lines. Haiti's quake was along the Enriquillo line—but the Septentrional fault that transverses the northern Dominican Republic is considered even more likely to experience a major quake. It's been building up fault pressure for 800 years.

By contrast, the Enriquillo had gone only 240 years since the last event—but the quake has raised the odds of a repeat. “This earthquake has increased the risk on other segments of that fault and perhaps on other faults as well,” a geologist tells the New York Times. An in-progress geological survey has shown that stresses have increased within 3 miles of Port-au-Prince. “The fault still stores sufficient strain to be released as a large, damaging earthquake during the lifetime of structures built during the reconstruction effort,” the survey warns.
(More Haiti earthquake stories.)