Quake/Tsunami

[Lamplighter]

The Guardian
Dec 7, 2011

Tsunami that struck Japan in March resulted from merging waves

(CNN) -- The devastating wall of water that struck Japan in March was the result
of at least two waves that combined to create a more powerful tsunami, U.S. scientists said Monday.

Ocean ridges and mountain ranges below the surface of the water channeled
the waves created by the 9.0 magnitude earthquake off the coast of Japan,
bringing them together far out at sea to form a "merging tsunami,"
according to researchers from NASA and Ohio State University.

The above link has a video, but the animation was running
too quickly to appreciate what was happening.
It's hard to see the merging waves on the east side of the epicenter (blue area).

I stepped through and at 17 sec finally got the image below.
This shows two waves (red) with a sliver of yellow in between, just to the left of the blue area.
In the next images, those two red areas merge into a single red band moving towards shore.