Japan quake caused rare double-wave tsunami: NASA

The massive earthquake off the coast of Japan in March caused a rare "merging tsunami" in which two waves combined to amplify the destruction after landfall, according to NASA.

For the first time ever, US and European radar satellites captured images of the two wave fronts, confirming the existence of the long-hypothesized process, which forms a "single, double-high wave far out at sea."

"This wave was capable of traveling long distances without losing power. Ocean ridges and undersea mountain chains pushed the waves together along certain directions from the tsunami's origin," NASA said in a statement on its website.

via ca.news.yahoo.com