US scientists find new cause of Haitian quake
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The magnitude 7.0 earthquake that struck Haiti early this year resulted not from the Enriquillo fault, as previously believed, but from slip on multiple faults, a new study reveals.
In addition, because the earthquake did not involve slip near Earth's surface, the study suggests that it did not release all of the strain that has built up on faults in the area over the past two centuries, meaning that future surface-rupturing earthquakes in this region are likely.
The study was conducted by a team of researchers from NASA's Jet Propulsion Loboratory (JPL), the U.S. Geological Survey (USGS), the California Institute of Technology and the University of Texas at Austin, the JPL said on Thursday.
The team used a combination of seismological observations, geologic field data and satellite geodetic measurements to analyze the earthquake source.
Initially the Haiti earthquake was thought to be the consequence of movement along a single fault -- the Enriquillo -- that accommodates the motion between the Caribbean and North American tectonic plates. But scientists in the field found no evidence of surface rupture on that fault.
The latest study found that the pattern of surface deformation was dominated by movement on a previously unknown, subsurface thrust fault, named the Leogane fault, which did not rupture the surface.
JPL geophysicist Eric Fielding, who processed synthetic aperture radar interferometry data from a Japan Aerospace Exploration Agency(JAXA) satellite used in the study, said, "I was surprised when I saw the satellite data showed the Haiti earthquake must have ruptured a different fault than the major Enriquillo fault, which everybody expected was the source. Without the radar images, we might still be wondering what happened."
Fielding said NASA images acquired after the earthquake over the major fault zones of Hispaniola by the JPL-built Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) airborne instrument will give scientists much more detailed information should another large earthquake occur in the region in the future.
Results of the study were published online this week in Nature Geoscience.
The Haitian quake, which took place in January, caused more than 200,000 casualties and devastated Haiti's economy.
