Japanese Devastation - result of merging waves
Baku, December 8 (AZERTAC). Researchers from NASA and Ohio State University have discovered that the deadly tsunami generated from the March 2011 Tohoku-Oki earthquake that devastated northeastern Japan resulted from merging waves, causing the killer tsunami to double in intensity over ocean ridges, and then amplifying its power upon landfall.
Data taken from NASA and European radar satellites captured at least two wave fronts during the events that day. The fronts merged to form a single, more intense wave far out at sea that was capable of traveling great distance without losing power. Ocean ridges and undersea mountain ranges pushed the waves together, but only along certain directions from the tsunami’s origin.
The discovery helps explain how tsunamis can cross ocean basins to cause significant destruction in certain areas while leaving other areas mostly untouched. Scientists hope the new findings will help improve tsunami forecasting.
The earthquake and tsunami together were responsible for more than 15,500 deaths in Japan. The events also led to a nuclear crisis at the Fukushima Daiichi Nuclear Power Plant, causing widespread chaos because of leaking radiation.
Three separate satellites passed over the region on March 11, during the tsunami. The NASA/Centre National d’Etudes Spaciales Jason-1 satellite, the NASA/European Jason-2 satellite and the European Space Agency’s EnviSAT, all carry a radar altimeter, which measures sea level changes to an accuracy of a few centimeters.
Each satellite crossed the tsunami at a different location. Jason-2 and EnviSAT measured wave heights of 8 inches and 12 inches, respectively. But as Jason-1 passed over the undersea Mid-Pacific Mountains to the east, it captured a wave front measuring 28 inches.
Tony Song and his team were able to verify the data through model simulations based on independent data, including GPS data from Japan and buoy data from the National Oceanic and Atmospheric Administration’s (NOAA) Deep-ocean Assessment and Reporting of Tsunamis program.
“Tools based on this research could help officials forecast the potential for tsunami jets to merge,” Song said. “This, in turn, could lead to more accurate coastal tsunami hazard maps to protect communities and critical infrastructure.”
The research was supported by NASA.
Results of the study were presented recently at an American Geophysical Union meeting.
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