Researchers discovered that the destructive tsunami generated by the March 2011 Tohoku-Oki earthquake was a long-hypothesized "merging tsunami" that doubled in intensity over rugged ocean ridges, amplifying its destructive power before reaching shore. Satellites captured not just one wave front that day, but at least two, which merged to form a single double-high wave far out at sea -- one capable of traveling long distances without losing its power....