[ken5050]

A question, if I may.....can anyone explain why the water on the shore at first gets sucked out to sea , as the wave nears?

In Thailiand, they said the sea bottom was exposed for over a thousand feet from the normal shoreline..

[Tennessee_Bob]

The wave has so much volume...as it travels through the ocean, it's using water in front of it - as it approaches the shore, it's pulling that water into itself. There's some footage from the Anchorage quake that shows the same phenomena (or however you spell it).

[spunkets]

"why the water on the shore at first gets sucked out to sea , as the wave nears?"

Waves are basically up and down motion. The water in the wave doesn't move sideways, the up/down motion does. The wave usually starts with a central down motion, then the water around it rises. As the wave crest moves, it is preceded and followed by a depressions. A depression hits first. THe depression is there, because the water to form the crest has to come from somewhere.

So when you see the water go out, the crest is forming- or, the the shot is being loaded.

In this case it looks like an island moved sideways ~100ft. On one side the water went up. On the other, it went down.

[randog]

Think of it as the 'trough', or low part of the wave, hitting first.