The Coming Atlantic Mega-Tsunami

rbrander writes "It's not news at all that scientists predict an eventual "mega-tsunami" that will sweep across the Atlantic that will still be anything from 60 to 150 ft high when it hits the U.S. Eastern seaboard. This Old News, however, suddenly seems fresh. Like an asteroid hit, it could be millenia away, or tomorrow, that a volcano in the Canary Islands just off Africa drops half a trillion tons of rock into the Atlantic. A short description of the problem from BBC News and some more graphic descriptions (of up to 100 million dead) and shrewd commentary on the politics of warning from journalist Gwynne Dyer."

Comments

Some bad science in the post

[Chairboy]

There's some bad science in the post, especially the comment about the wave being 'still' that high. Most tsunamis are very small out in the ocean, most less then a few centimeters tall.

They don't get big until they approach the shore and the depth gets shallow.

The small waves, btw, travel around the speed of a jetliner, hence the lack of warning.

Wave Height

[bzebarth]

that will sweep across the Atlantic that will still be anything from 60 to 150 ft high when it hits the U.S. Eastern seaboard

I heard an interview with someone from NOAA with the Pacific Marine Environmental Laboratory in Seatle that described what happens when a Tsunami occurs. He said when the wave travels through deep water it has tremendous speed (hundreds of mile/hour) but is only a few feet high. As it comes into shallow water the wave slows down to 10s of miles/hour and that causes the huge wall of water. So a Tsunami is not really a 100 ft wave as it travels through the ocean only once it nears land.

Just my $.02.

Bad computer models exagerate La Palama tsunami?

[Curses! Curses!]

From: http://www.drgeorgepc.com/TsunamiMegaEvaluation.ht ml/

A collapse of Cumbre Vieja will not generate waves of up to 50 m. in height in Florida and the Caribbean islands, or more than 40 m along the northern coast of Brazil, ... Proper modeling of dispersive effects (Mader 2001) - provides much more realistic far-field wave estimates, in the unlikely event of a large-scale, La Palma slope failure. Mader's model of a La Palma slide estimates that the east coast of the U.S. and the Caribbean would receive tsunami waves of less than 3 meters and the European and African coasts would receive waves less than 10 meters high. However, this represents the upper limit. Full Navier-Stokes modeling brings the maximum expected tsunami wave amplitude off the U.S. east coast to about one meter. Even with shoaling effects, a tsunami from a La Palma slide would still be of concern but does not present an unmanageable threat or a significant far field hazard.

That's a three foot wave hitting the U.S. Eastern seaboard after a worst case collapse at La Palma. The paper is very detailed and worth a read.

Lots of hype, poor science

[craw]

This is what the real experts think about this. The topic of the mega-tsunami is at the end of the FAQ. So
read it and learn something.

Note that one could point to a lot of active oceanic volcanoes and pose a similar threat level if one considers a tens of thousand of years time frame.

Another side note: When I was in grad school, I was the TA for one of the committee members.

Re:Wikipedia

[NearlyHeadless]

One should note that the prediction of this megatsunami is very much the minority position among scientists.

See Tidal wave threat 'over-hyped' at the BBC web site, and this statement from the Tsunami Society:

MEGA TSUNAMI HAZARDS
January 15, 2003

The mission of the Tsunami Society includes "the dissemination of knowledge about tsunamis to scientists, officials, and the public". We have established a committee of private, university, and government scientists to accomplish part of this goal by correcting misleading or invalid information released to public about this hazard. We can supply both valid, correct and important information and advice to the public, and the names of reputable scientists active in the field of tsunami, who can provide such information.

Most recently, the Discovery Channel has replayed a program alleging potential destruction of coastal areas of the Atlantic by tsunami waves which might be generated in the near future by a volcanic collapse in the Canary Islands. Other reports have involved a smaller but similar catastrophe from Kilauea volcano on the island of Hawai`i. They like to call these occurences "mega tsunamis". We would like to halt the scaremongering from these unfounded reports. We wish to provide the media with factual information so that the public can be properly informed about actual hazards of tsunamis and their mitigation.

Here are a set of facts, agreed on by committee members, about the claims in these reports:

- While the active volcano of Cumbre Vieja on Las Palma is expected to erupt again, it will not send a large part of the island into the ocean, though small landslides may occur. The Discovery program does not bring out in the interviews that such volcanic collapses are extremely rare events, separated in geologic time by thousands or even millions of years.

- No such event - a mega tsunami - has occurred in either the Atlantic or Pacific oceans in recorded history. NONE.

- The colossal collapses of Krakatau or Santorin (the two most similar known happenings) generated catastrophic waves in the immediate area but hazardous waves did not propagate to distant shores. Carefully performed numerical and experimental model experiments on such events and of the postulated Las Palma event verify that the relatively short waves from these small, though intense, occurrences do not travel as do tsunami waves from a major earthquake.

- The U.S. volcano observatory, situated on Kilauea, near the current eruption, states that there is no likelihood of that part of the island breaking off into the ocean.

- These considerations have been published in journals and discussed at conferences sponsored by the Tsunami Society.

Some papers on this subject include:

"Evaluation of the threat of Mega Tsunami Generation From ....Volcanoes on La Palma ... and Hawaii", George Pararas-Carayannis, in Science of Tsunami Hazards, Vol 20, No.5, pages 251-277, 2002.

"Modeling the La Palma Landslide Tsunami", Charles L. Mader, in Science of Tsunami Hazards, Vol. 19, No. 3, pages 160-180, 2001.

"Volcano Growth and the Evolution of the Island of Hawaii", J.G. Moore and D.A.Clague, in the Geologic Society of America Bulletin, 104, 1992.

Committee members for this report include:

Mr. George Curtis, Hilo, HI (Committee Chairman) 808-963-6670

Dr. Tad Murty, Ottawa, Canada, 613-731-8900

Dr. Laura Kong, Honolulu, HI, 808-532-6422

Dr. George Pararas-Carayannis, Honolulu, HI, 808-943-1150

Dr. Charles L. Mader, Los Alamos, NM, 808-396-9855

and all can comment on this or other tsunami matters.

For information regarding the Tsunami Society and its publications, visit: www.sthjo