Washington: A NASA team has successfully demonstrated a prototype tsunami prediction system that will help researchers gauge large earthquakes and estimates the size of resulting tsunamis accurately.
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 predict the size of the resulting tsunami. The network can estimate their positions every second and detect ground motions as small as a few centimetres.
"This successful test demonstrates that coastal GPS systems can effectively be used to predict the size of tsunamis," said Song.
"This could allow responsible agencies to issue better warnings that can save lives and reduce false alarms that can unnecessarily disturb the lives of coastal residents."
John LaBrecque, manager of the Solid Earth and Natural Hazards program in the Earth Science Division of NASA's Science Mission Directorate in Washington, said, "The value of coordinated real-time observations from precision GPS, satellite altimetry and advanced Earth models has been demonstrated."
Song’s prediction method relies on data from coastal GPS stations near an epicenter, along with information about the local continental slope to estimate the energy an undersea earthquake transfers to the ocean to generate a tsunami. Previous tsunami models presume a tsunami’s power is determined by how much the seafloor is displaced vertically due to an earthquake. But this theory has failed in the past. Now, Song’s theory says that continental slope also contributes to a tsunami’s power by transferring kinetic energy to the ocean.
When the Feb. 27 earthquake struck, its ground motion was captured by the NASA GDGPS network’s station in Santiago, Chile, about 146 miles from the earthquake’s epicenter. These data were made available to Song within minutes of the earthquake, enabling him to derive the seafloor motions.
Based on these GPS data, Song calculated 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 detected by GPS indicated the slip of the fault transferred fairly little kinetic energy to the ocean.
The theory is further substantiated in a recently accepted research paper by Song and co-author Shin-Chan Han of NASA's Goddard Space Flight Center, Greenbelt, Md.
First Published: Tuesday, June 15, 2010, 15:06