The tsunami at Kesennuma

YouTube link.

Video of the sequence of events at Kesennuma changed my entire conception of how a tsunami works.  The link discussed at this Reddit thread is now dead, but I think the one I have embedded above is a duplicate; please view today, since I'm not sure whether it will be pulled.

My views of tsunamis had been most strongly influenced by the one in the Indian Ocean in 2004.  A memorable video of that event is backed by haunting Breton music by Denez Prigent and Lisa Gerrard.  In the Indian Ocean tsunami, the images were of the sea pulling back from the coastline, a giant wave crashing ashore, and then the water retreating and sucking debris and people out to sea.

The Japanese tsunami is different.  It's not a giant wave so much as it is the entire ocean moving ashore.  In the video above, the water hits - but then it keeps coming and keeps coming and keeps coming.  The relentless nature of the onrushing water is jaw-dropping.  It seems to me that when the fault line shifted, the seabed offshore from this region must have lifted up (not just shifted horizontally, which might cause a single concussive wave as in the Indian Ocean), and after the seabed rose, the several ?hundred square miles of ocean above the plate must have spilled off to the side and headed outwards, including towards shore.