AUSTIN, Texas, Aug. 2 (UPI) -- U.S. scientists used satellite gravity measurements to determine recent Pacific Rim earthquakes produced deformations in Earth's gravity field.
University of Texas at Austin scientists led by J.L. Chen of the school's Center for Space Research used the satellite data to estimate changes in groundwater storage, sea level and polar ice sheet extent.
The study, they say, provided a unique way to monitor deformation associated with major earthquakes, supplementing global positioning system measurements that are limited if earthquakes occur off shore.
The researchers focused on effects of seismic deformation due to ruptures from the magnitude 9.3 Sumatra-Andaman earthquake on Dec. 26, 2004, and its companion magnitude 8.7 Nias earthquake occurring March 28, 2005.
The scientists found gravitational field disturbances caused by the earthquakes extend more than 1,100 miles along the Andaman and Sunda subduction zones. The researchers posit the gravity changes are due to afterslip, viscous relaxation of the upper mantle, or other processes associated with upper mantle recovery after such great earthquakes.
The research is detailed in the journal Geophysical Research Letters.
