Japanese and California scientists are now reporting they were able to track the March 11 tsunami on radar.  It was the first time a tsunami was observed on radar.

For the past ten years, scientists from California and Japan, have been using radar to track ocean currents. They discovered they could track large tsunamis as well.

The radar did not pick up the actual tsunami surge, but the changes in the ocean currents caused by the surge.  The scientists hope radar could be used as an tsunami early warning system.