The Geology Underlying the Devastating Haiti Earthquake

From The Christian Science Monitor:

The magnitude 7 earthquake that leveled much of Haiti’s capital Tuesday – the strongest temblor to hit the country in some 200 years — may have increased strain on a segment of the same fault that lies across the border in the Dominican Republic.

That concern, based on calculations made during the first 24 hours after the quake hit, may ease with additional on-the-ground data, cautions Purdue University geophysicist Eric Calais, who has spent years studying faults on Hispaniola, the island both countries share.

But since the mid-1980s and the advent of precision satellite measurements of ground movement, plus other high-tech advances, earth scientists have developed an increasing respect for the ability of the slip of one fault to increase the strain on other, nearby faults, or on a different segment of the original fault.

In any effort to track changes in strain, “I would focus on the eastern termination of the fault towards the Dominican Republic, pending more information,” he says. The reason: The rupture slid to the east. While strain would build at both ends of the ruptured segment, another rupture farther to the west would occur in a sparsely populated, hard to reach portion of Haiti. To the east, however, the fault traces a path through the mountains separating Haiti from the Dominican Republic and into the more-heavily populated southwestern portion of Haiti’s neighbor.