Acehtsunami

A NASA-led research team has successfully displayed for the first time elements of a prototype tsunami prediction system that quickly and accurately assesses large earthquakes and estimates the size of resulting tsunamis. After the magnitude 8.8 Chilean earthquake on Feb. 27, a team led by Y. Tony Song of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., used real-time data from the agency’s Global Differential GPS (GDGPS) network to successfully foresee the size of the resulting tsunami. The network, managed by JPL, unites global and regional real-time data from hundreds of GPS sites and estimates their positions every second. It can detect ground motions as small as a few centimeters.

When the Feb. 27, 2010, earthquake struck, its ground movement was captured by the NASA GDGPS network’s station in Santiago, Chile, about 235 kilometers (146 miles) from the earthquake’s epicenter. These data were made accessible to Song within minutes of the earthquake, enabling him to derive the seafloor motions. Based on these GPS data, Song determined the tsunami’s source energy, ranking it as moderate: a 4.8 on the system’s 10-point scale (10 being most destructive). His conclusion was based on the fact that the ground motion identified by GPS indicated the slip of the fault transferred fairly minimal kinetic energy to the ocean.

“We were fortunate to have a station sufficiently close to the epicenter,” delivered Yoaz Bar-Sever, JPL manager of the GDGPS system. “Broad international collaboration is required to densify the GPS tracking network so that it adequately covers all the fault zones that can give rise to large earthquakes around the world.”