No Wonder It Was So Bad: Japan Had Two Tsunamis They merged into an ultra-powerful wave By John Johnson, Newser Staff Posted Dec 6, 2011 12:39 PM CST 6 comments Comments In this photo taken March 27, 2011, a resident wipes her tears as she views her destroyed neighborhood from atop Weather Hill in Natori, Miyagi Prefecture, northeastern Japan. (AP Photo/Wally Santana) (Newser) – This might explain why the tsunami that devastated Japan in March caused so much death and destruction: Scientists think it was actually two tsunamis that merged into one uber-powerful wave, reports CNN. Satellites show two wave fronts combining far out at sea to create a tsunami double the normal height and intensity. The phenomenon is called "merging tsunami," and it had previously existed only in theory, notes NASA. "It was a one in 10 million chance that we were able to observe this double wave with satellites," says one NASA scientist. "Nobody had definitively observed a merging tsunami until now." Ocean ridges and underwater mountain ranges helped direct the waves toward each other, and the discovery could help better predict future ones around the world, adds an Ohio State researcher.