Well, when tectonic plates beneath the Earth, that causes a ripple effect that...

I could use an explanation, too. =/

What I remember from my geophysics class is that when an earthquake occurs in the ocean it instantly displaces a large amount of water, which then collapses due to gravity and forms a high velocity, low amplitude wave. As the wave approaches shallow water, it slows down and increases in amplitude, and that's the tsunami.

But I'm sure someone else could give a better explanation.

._.

I mean this one that everybody is talking about.

._.

I mean this one that everybody is talking about.

A magnificent tsunami hit Japan -- it's one of the worst in recorded history.

And, now, it's heading west, and might be hitting the west coast.

There was a pretty strong earthquake off the coast of Japan which resulted in a tsunami (which spreads out in a circle like a gigantic ripple). Japan was hit pretty hard, and other warnings were issued to coasts which the tsunami may or may not reach. Hawaii sounds like it might have some tsunami activity, and the California coast was issued a tsunami warning. It seems that other various islands/island chains (such as Guam and the Philippines) were issued warnings as well. Basically any country in the Pacific region.