David Umberger2

David Umberger2

Researchers found a previously unmapped fault was responsible for the devastating Jan. 12 earthquake in Haiti and that the originally blamed fault remains ready to produce a large earthquake. Eric Calais, a Purdue University professor of earth and atmospheric sciences, led the team that was the first on the ground in Haiti after the magnitude 7.0 earthquake, which killed more than 200,000 people and left 1.5 million homeless.The team determined the earthquake’s origin is a previously unmapped fault, which they named the LÄogëne fault. The newly discovered fault runs almost parallel to the Enriquillo fault, which was originally thought to be the source of the earthquake, he said.

“This means that the Enriquillo fault is still capable of producing large earthquakes and that Haiti has to adapt to this seismic hazard,” said Calais, who in September was appointed science adviser for the United Nations Development Program in Haiti. “The fault system is more complex than we originally thought, and we don’t yet know how the January earthquake impacted the other faults. Preliminary measurements indicate that the Enriquillo fault did not release any accumulated seismic energy and, therefore, remains a significant threat for Haiti, and Port-au-Prince in particular. We need to investigate the fault system further to be able to determine where the next earthquakes might occur and how large they could be.”The shifting of the Earth’s crust after a major earthquake can add to or reduce stresses building up in nearby faults and can apply pressures that effectively stop or release other earthquakes. Because of this, the earthquake along the Léogâne fault may have delayed or advanced the timing for the next earthquake on the Enriquillo fault, he said.

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