The earthquake that struck Haiti on Saturday morning occurred on the same system of faults as the one that devastated the capital, Port-au-Prince, in January 2010. And the previous quake almost certainly made this one more likely to occur. Both quakes struck on an east-west fault line at the convergence of two tectonic plates, large segments of the Earth’s crust that slowly move in relationship to each other. At this fault line, called the Enriquillo-Plantain Garden fault zone, the Caribbean plate and the North American plate move laterally, or side by side, at a rate of about a quarter of an inch a year, The New York Times reported.
