Floyd take a look at the tsunami in japan - bezzle has some videos of footage of 100+ft i think

Japan Tsunami 8ish feet - 240cm

According to Wikipedia, Raleigh is 315 ft (96 m) elevation. So a 100 ft tsunami wouldn't make it that far but a 100 m one might. It is about 2 hours from the closest beach so maybe 120 miles? Don't know how fast the momentum would fall as it traveled over land.

Quote:

Don't know how fast the momentum would fall as it traveled over land.

I know one thing for sure. If a Tsunami ever came from the Atlantic, I SURE AS HELL wouldn't want to be on the NC Outer Banks!!! I doubt there would be anything at all left of the islands afterward. They would be effectively 'erased' from the map.

As an afterthought, I wonder what kind of scenario would have to unfold to send one up into DC. It would probably have to come from a direction that would send it into the Chesapeake, and up the Potomac. It would probably burn itself out before going that far up the river.

Rarnopp - I was blissfully unaware of that. Now I have to add salty wet fish doom to my list of worries. You git.

Off to check my elevation

Thanks Asi, Dj, Knob, Sdbn. Crazy to think that the Japan tsunami was only 8 ft!

Yeah Darth, the Outer Banks are a great place to visit or have a second home...srely not a place for permanent residence when you think about its elevation. Kinda makes me want to have a place in the Smokeys...

Floyd: It was A LOT higher than 8'. In places it was well over 100'

I might get my waterfront property yet

Ntb -

Check more than elevation. Here's the way I think about potential tsunami effects:

The primary determinants of the total amount of energy available to cause devastation are the magnitude of the displacement from mean sea level and the wave speed, both as measured in the open ocean.

The original wave speed, the slope towards the shoreline, and the shape of the shoreline where the tsunami wavefront hits will determine the wave height, direction, and speed upon landfall. Once the wave hits the land, the slope and shape of various land features determine the channelization, the energy dissipation, and the wave height and speed (i.e., the amount and distribution of damage) at any point inland.

If that is correct, then one may see much greater devastation from a 1 foot open ocean height tsunami in certain locations than other locations might experience from a 10 foot open ocean height tsunami, even if both locations are equidistant from the source. In theory, a 1 foot open ocean height tsunami may cause a 100 foot wall of water in some places. Therefore, I believe it is waaaay too simplistic to just look at the elevation to evaluate whether one might suffer ill effects from a tsunami.

If one is many miles inland, elevation is probably not a bad first order indicator. But if it's only a couple of miles inland, I sure wouldn't feel comfortable that I'm assuring the safety of my family by using just elevation to make that call.

Cheers Peter. I'm 67M above sea level and about as far from the sea as it is possible to get in the UK. If I end up with a lobster up my ass there ain't going to be many survivors I guess.

Ntb -

If you're that far inland, I would imagine you'd probably be justified in removing tsunamis from your list of "Top 1000 Things to Worry About".

http://sos.noaa.gov/datasets/Ocean/japan....

From NOAA. Slightly higher than my previous erroneous post.

Volcanic activity has always been on my personal radar screen.

That's why I live over 100 miles from the coast, and at an elevation to boot.

But, I always been sort of an "earth changes" doomer :)

What a 100ft tsunami looks like:

Personally I have a hard time believing that a land slide on other side of the world would create a 100'+ wave on the east coast. First of all origin of the Japanese tsunami was just off the coast. The massive Alaskan tsunami was also didn't travel very far. I would also hazard to guess that the Japanese earthquake moved a much bigger land mass than a land slide on La Palma would. It seems all your really big tsunamis are either local events or asteroid caused.

Simple physics energy in should equal energy out. Can you imagine the amount of energy it would take to cover the east coast with 100' of water? Even if the whole island was thrown into the sea I don't think you have enough energy.


If you want some technical reading http://www.drgeorgepc.com/TsunamiMegaEva....

Earthquake Report's Coverage: http://earthquake-report.com/2011/09/25/....

Chris I know its hard to believe but it does happen. Energy is really irrelevant. Its the Displacement that causes the Tsunami.

Chris: Do some research on Lituya bay.

[Edit: And on soliton waves, particularly in the open ocean.]

38.442001,141.447144

Is the location of the camera in the top left video in Bezzle's post.

The cameraman is standing on the roof at the very highest point of a 6 or 7 storey building.

That particular inlet was flooded 5 km inland.

Asimov Lituya bay was a closed isolated body of water with perfect bathymetry for a massive wave.

Can you show me any examples of a landslide causing a massive tsunami in the open ocean?

Since the waves propagate in a 360 degree action wave intensity reduces in a non linear way.

Abe it is ALL about energy. Displacement is how the energy is applied. If you think you can get more energy out at the end of the wave than you put in... I have a perpetual motion machine to sell you.



Did anybody look at the link I supplied I would like to hear a good criticism of it.

Chris92346 -

2 things you don't seem to be considering.

First, it's simply a wave in the ocean - there is essentially NO material propagation, merely wave energy moving through the water, i.e., the water at the source of the tsunami does NOT travel to the point of of landfall however near or distant it may be. Thus, you can't look at the energy dissipation over distance the same way that kinetic energy is lost due to frictional forces that manifest themselves when an object (or even a mass of water) travels through the ocean - totally different mechanism.

Second, nobody ever said anything about getting more energy out than goes in. The total energy driving the water up the land is a function of the width of the wave that impacts the land (for all practical purposes, the width can be considered as a straight line rather than an arc, unless the source of the tsunami really close to the landfall), i.e., all other things being equal, a 1000 m wide wavefront contains twice the energy of 500 m of wavefront. Now, consider the effects of coastal reefs, rocks, bays, river deltas, etc. that channel a 1000 m portion of wavefront in such a way that it is only 100 m wide when it hits the shoreline. Thus, for that 100 m wide section of shoreline, it is equivalent to being hit with a 10 times bigger wave than a 1000 m wide segment of shoreline for which the impinging wavefront had not been channelized. Total energy at landfall in both instances is the same, but the effects on the narrow segment are 10 times worse than the wide one (close enough for gov't work - there is some energy dissipated in the channeling process). If the topography behind the 100 m and 1000 m wide landfalls are the same, the inland effects are very different and the intrusion of the 100 m wavefront (which was originally a 1000 m wide wavefront) will be to much higher elevations.

Chris: http://www.es.ucsc.edu/~ward/papers/sing....

2nd result on google search for "large tsunami landslide"

There are plenty more. And yes, real evidence, not conjecture. Like the norfolk canyon landslide, the storegga landslide and the nauuanu (hawaii) landslide. All researched and described in depth.

There's less evidence for landslide generated tsunamis because they are usually caused by earthquakes and the quake gets the blame. In the past, the assumption was ALWAYS that it was the earthquake, only in more recent times has the danger of oceanic basin wide tsunamis caused by nothing but landslides come to light.

There's plenty more here, if you bother to look: http://www.google.com/search?client=oper....

For you geology buffs, what's the range around the word "imminent" in geological terms?