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Friday, August 20, 2004

La Palma Mega-Tsunami?

Last week, Bill McGuire of the Benfield Hazard Research Centre in London was again pushing his theory that a collapse of the volcanic island La Palma in the Canary Islands is likely to cause a "mega-tsunami" that could cause a giant wave crashing into much of the United States. This was also the subject of a BBC documentary which has been shown several times on the Discovery Channel.

Well, don't worry too much. Tsunami experts have looked into the theory and don't consider it much of a threat. First, they expect La Palma to collapse in many small landslides, not one giant one. And, second, even if the worst case collapse did occur, the wave would be much smaller than McGuire says. A three foot-high wave looks to be the biggest that could hit the U.S., not a 200 foot-high wave. Note that in the documentary, the example they give of a mega-tsunami is a landslide in a bay. In the open ocean a wave would behave considerably different. To quote a committe of the Tsunami Society:

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.

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Thursday, August 19, 2004

Bush's Exit Strategy

The news this week that President Bush is planning for the long overdue reduction of troops in Europe and Asia reminded me of a conversation I had recently with my parents. They had both been reading The Sorrows of Empire : Militarism, Secrecy, and the End of the Republic by Chalmers Johnson. One fact from the book that they found dismaying was that the U.S. has over 700 military bases in foreign countries.

I did some web research and found the Base Structure Report. Sure enough, there are 702 foreign bases. Well, 702 foreign installations, anyway. The Aviano air base in Italy actually comprises some eight installations: the main base and seven annexes for housing, administration, and storage. Of the 702 installations, 312 are in Germany. If you add up Germany, Italy, the United Kingom, South Korea, and Japan, you get (if I count correctly) 598. So, 85% of the bases are in just five countries.

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