Haiti quake caused by 'new fault'
The devastating earthquake that rocked Haiti in January was unleashed by a previously undetected fault line - not the well-known one initially blamed, according to an analysis of new data.
It is unclear how dangerous the new, unmapped fault might be or how its discovery changes the overall earthquake hazard risk for Haiti, said Eric Calais, a professor of geophysics at Purdue University in West Lafayette, Indiana, who presented the findings this week at a scientific conference in Brazil.
He said the analysis shows that most, if not all, of the geologic movement that caused January's magnitude-7.0 earthquake occurred along the newly uncovered fault, not the well-documented Enriquillo fault.
He said that suggests Haiti's seismic zone is far more complex than scientists anticipated. But the new fault's profile, including the possibility that it merges with the Enriquillo fault at some depth, will not be known until scientists intensively study the region.
"If there are other faults capable of producing earthquakes besides the Enriquillo and this new one we need to know about them. We need to go after them," he said from Brazil by telephone.
Prof Calais said that at the time of the quake, Haiti had no seismic stations. Researchers who flocked to the Caribbean nation since installed about 10 stations to monitor the earth's movement.
Bruce Presgrave, a geophysicist with the US Geological Survey, said the discovery is the sort of revelation that often comes to light after big earthquakes, when scientists descend on quake-ravaged sites to conduct intensive research.
"It's part of the learning process of science," he said. "They're doing detailed studies of the area that aren't possible in the hours following the quake."