How tsunami develop

New Zealand government, BBC ^ | 12-28-04 | BBC News correspondent Alex Kirby

[G32]

I guess the movie Deep Impact got it pretty close.

[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..

[Imaverygooddriver]

A tsunami is made up of a series of travelling ocean waves of extremely long wavelength. They are triggered by large disturbances such as earthquakes, undersea volcanic eruptions or deep sea landslides.

Or Ted Kennedy immediately belly flopping off the side of his yacht to get a bottle of bourbon he knocked overboard.

[MahaMarty]

Or if her forgot something important in a submersed '69 Cadillac.

[twntaipan]

Fascinating video of the tsunami hitting a SE Asian beach resort (Thailand?) is found at this link: http://homepage.mac.com/jlgolson/tsunami.wmv

[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).

[ken5050]

OK..I think I get it..at first glance..it's counter-intuitive..

[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.

[ken5050]

OK..thanks..makes sense...cogent explanation.....now, "can I have some more, sir?" (G)

I've read how the tsunami are formed at the epicenter of the quake site..the movement of the sea floor rapidly, and violently, displaces water..which is not compressible..thus generating a wave..I got thataprt. The sea floor can be thrust up, or the opposite..it can collapse...will both activities generate a tsunami..and the same type, and with the same direction?..if the bottom collapses...water rushes in, right..does the wave run TOWARDS the epicenter?

Thanks again..

[Asfarastheeastisfromthewest...]

Revelation 16:18 And there were voices, and thunders, and lightnings; and there was a great earthquake, such as was not since men were upon the earth, so mighty an earthquake, and so great.19 And the great city was divided into three parts, and the cities of the nations fell: and great Babylon came in remembrance before God, to give unto her the cup of the wine of the fierceness of his wrath. 20And every island fled away, and the mountains were not found.

Ah, you ain't seen nuthin' yet!

[shubi]

I just heard a reputable scientist say it is unlikely we would have a tsunami on the east coast because the plates move horizontally not vertically.

[randog]

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

[cdbull23]

know of any links to see this footage?


thanks :)

[shubi]

I don't think those two men who were trying to reach to porch made it. This was a dramatic piece of footage that shows the immense power of a tsunamis and the extreme duration. This was apparently the second or third wave.

[Vn_survivor_67-68]

I second your opinion of spunkets reply......

I found this while trying to inderstand it....might interest you or others, too:

The Physics of Tsunamis
The mechanisms of tsunami generation and propagation

sections:
What does "tsunami" mean?
How do tsunamis differ from other water waves?
How do earthquakes generate tsunamis?
How do landslides, volcanic eruptions, and meteorites generate tsunamis?
What happens to a tsunami as it approaches land?
What happens when a tsunami encounters land?

http://www.geophys.washington.edu/tsunami/general/physics/physics.html

[ken5050]

Thnks for the link..took a while to load..the server must be swamped..bookmarked for tonite late.

[M. Espinola]

Deep Impact had great graphic effects.

[Tennessee_Bob]

I've never seen it on the web - just did a quick and dirty search and couldn't find it - but I've seen it plenty of times on television. It's 8mm, black and white and grainy, but you can see what's going on in it.

[mund1011]

I believe the distinguished drunk from Massachusettes was the captain of an Oldsmobile.