Tokyo, Japan: The tsunami that devastated the north-east coast of Japan on March 11 was created by at least two wave fronts that merged to form a far more destructive ”double tsunami”, according to NASA and researchers at Ohio State University.
NASA said two of its satellites and a European satellite happened to be passing over the tsunami on the day of the disaster. They were equipped with instruments capable of measuring changes in sea levels to an accuracy of a few centimetres.
”Nobody had definitively observed a merging tsunami until now,” said Y. Tony Song, a research scientist at NASA’s jet propulsion laboratory in California. ”It was a one in 10 million chance that we were able to observe this double wave with satellites.”
Dr Song said the same phenomenon could have caused the Chilean tsunami in 1960, in which 200 people in Japan and Hawaii were killed.
Scientists say the data will improve their understanding of how tsunamis move across oceans, and may help them improve tsunami forecasts.
”Tools based on this research could help officials forecast the potential for tsunami jets to merge,” Dr Song said. ”This in turn could lead to more accurate coastal tsunami hazard maps to protect communities.”
The researchers said they had verified their findings using independent data, including GPS readings from Japan.