Tuesday, December 02, 2008

Discovery Channel Sci-Tech: New York Earthquake


Tonight the Discovery Channel aired a one-hour film “New York Earthquake” as part of its Sci-Tech series. It is very similar to the History Channel Mega-Disasters film of the same name which I reviewed on this blog Oct. 23, 2007 but it does not seem to be identical. The credits say that it was made for Discovery Channel (they rolled too fast to get the name of the director).

The film seemed to me more specific as to the danger New York could be in than I recall from the History Channel film. As before, it mentioned the 1884 earthquake, magnitude 5.5, south of Long Island. As a general rule, earthquakes in the East for a given magnitude are more destructive and over a wider area than in California. A 6.0 in New York City (which could happen ever 400 years) might be more destructive as a whole than a 7.0 in San Francisco, despite the logarithmic nature of earthquake Richter scale. A 7.0 could happen every 3500 years, but no one know when the last “big one” was so the clock could be ticking now.

This film (a scientist named Gates) examined the mountains north of New York City (Harriman Park, perhaps the Schewangunks, a popular destination for the Sierra Club when I lived there) for active faults, and found a fault that could explain the 1884 quake.

A physicist (Steve Ross, native of the City) discussed the vulnerability of bridges and buildings in New York. Masonry buildings without reinforcing steel, common in brownstones, could collapse. The external masonry from older skyscrapers like the Empire State Building could fall off as if shaved. Shorter buildings have higher natural frequencies and are more exposed to mechanical resonance. Some bridges have only vertical steel support and are vulnerable. The Roosevelt Island tram (which I rode in 1976 and actually looked at an apartment – too much trouble) is vulnerable. So are some apartment buildings built over the East Side or West Side highways. Some subway tunnels are not sufficiently reinforced.

The bedrock underneath New York City varies in thickness, which explains why skyscrapers generally are built only at the lower end and in midtown.

New York does sit in the middle of a plate now, but there are very old faults underneath, and possibly some dimpling, as with New Madrid. Boston and Charleston SC have had severe earthquakes since the settlement of America.

Most of New York City remained functional on 9/11. That would not be true after a major earthquake.

Chuck Scarborough, former local television anchor in New York, appears in the film. He is author of "Aftershock: Earthquake in New York", which became the four hour film (1999, directed by Mikhael Solomon) that has appeared on ION TV. (There is also a 1998 shorter TV film by that name, directed by Terry Ingram.)

So, Donald Trump, watch out. The City can eat people up.

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