What is the proper response to a tsunani?

[Peter Brennan]

The difference

between a storm surge and a tsunami is, I suspect, substantial. A storm surge is just wind-driven water on top of the normal tide that raises water level in the affcetd region for a period of time. Like a flood on a river, it crests, then subsides as the water drains back to the sea and the wind dies down. It has neither wave length nor forward velocity though it does have amplitude. A tsunami, though, is an energy-carrying wave with a wave length of many miles, a speed approaching 500 MPH, and a tiny amplitude when at sea. As it shoals, its amplitude increases, its speed decreases and all that energy becvcomes concentrated in a small region. It doesn't just rise and flood the land. It smashes into the land and carries all before it. The continental shelf might well put the brakes on a tsunami aimed at the US East Coast, but do you really want to see the bottom suddenly appear all the way to the 100 fathom line, then have the sea rush back in?

 

[eds928gt]

The storm surge would probably be worse.

At least along the US Atlantic coast. It would likely last much longer than a tsunami, and it would have a greater amplitude during that time. The speed of the tsunami in the open ocean gets drastically reduced as it is affected by the seafloor. Thus, it's speed is not what causes devestation. It's the amplitude of the wave that creates the majority of the damage.As mentioned, the tsunami that wiped-out the harbor of Lisbon, Portugal in 1755 barely made it to the 'Colonies'. It most likely spent a great amount of its enegy breaking on the relatively shallow US Atlantic Continental Shelf.BTW, I've seen the devestation from storm surges. Were it not for advanced warnings and sparcely populated coastal areas, the death toll could easily surpass that of a tsunami. Certainly, the property damage can be more than a tsunami. Just ask the folks in SC about Hugo.~ Happy sails to you ~ _/) ~

 

[P hunter]

Tsunami- Japanese for "Big Ass Wave"

All the Japanese yoy need to know!

 

[John Dawson]

Photos and stories

from yachts at the tsunami, curtesy of the Alberg group.

 

[Bil]

Pics of It Coming Ashore

You might find actual pics of the waves coming ashore, thru the morring field interesting. If your in deep enough water hold on, grab your camera and watch it unfold.

 

[eds928gt]

Very interesting photos and descriptions.

I read that one of the boats was anchored fairly close to shore (from the photo, it looks like 1000' out) in 40' of water. If you check the charts for the US Atlantic, you will be hard pressed to find 40' water depths within a 1/4 mile from shore. In most places (except for channels), the depth will be about 10' or less. Off the coast of NJ, it might be even less than 5'.Thus, it seems likely that if that same tsunami were to make it to the east coast of the USA, it would have felt the bottom farther offshore, and would have already crested and broken before it reached the shore. There would likely be a surge, but not of the magnitude seen in those (excellent) photos.~ Happy sails to you ~