The tsunami that devastated northeastern Japan in March 2011 was the product of two wave fronts merging far out at sea, according to new research from NASA and Ohio State University.
A NASA-Centre National d'Etudes Spaciales satellite captured images of the waves forming and merging far off the coast of Japan.
Once the two waves combined, the wave could travel long distances without losing power. Undersea mountains chains and ridges pushed the waves together.
Undersea topography is used to create hazard maps for where tsunamis are likely to strike. But such maps tend to focus on mountains and ridges located close to shore. Scientists may now be able to develop maps that take undersea topography far off shore into account.