The geology underlying the devastating Haiti earthquake
The same earthquake fault that lies under Haiti also runs through the Dominican Republic. Geologists warn that the Haiti quake – at the Enriquilla-Plantain Garden Fault – may have added strain elsewhere and more quakes are possible.
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.Skip to next paragraph
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.
Already, teams of researchers are planning to visit the stricken area to take the full measure of the quake before erosion or rebuilding efforts erase key pieces of evidence.
Accurate measurements of ground movement -- seen in offset stream beds or displaced roads, for instance -- help establish the amount of strain released. Careful monitoring of the strongest aftershocks, which can die off fairly quickly after a quake, help establish how deep in the crust the quake's break-point was. Tracking the quake's aftermath over the long term will help researchers better understand the slow rebound that occurs along the fault after the initial snap.
Why Haiti's fault got less attention