Earthquakes endanger New York more than previously believed

50-year period would be 7 percent and 1.5 percent. After less specific hints of these possibilities appeared in previous research, a 2003 analysis by The New York City Area Consortium for Earthquake Loss Mitigation put the cost of quakes this size in the metro New York area at $39 billion to $197 billion. A separate 2001 analysis for northern New Jersey’s Bergen County estimates that a magnitude 7 would destroy 14,000 buildings and damage 180,000 in that area alone. The researchers point out that no one knows when the last such events occurred, and say no one can predict when they next might come.

“We need to step backward from the simple old model, where you worry about one large, obvious fault, like they do in California,” said coauthor Leonardo Seeber. “The problem here comes from many subtle faults. We now see there is earthquake activity on them. Each one is small, but when you add them up, they are probably more dangerous than we thought. We need to take a very close look.” Seeber says that because the faults are mostly invisible at the surface and move infrequently, a big quake could easily hit one not yet identified. “The probability is not zero, and the damage could be great,” he said. “It could be like something out of a Greek myth.”

The researchers found concrete evidence for one significant previously unknown structure: an active seismic zone running at least twenty-five miles from Stamford, Connecticut, to the Hudson Valley town of Peekskill, New York, where it passes less than a mile north of the Indian Point nuclear power plant. The Stamford-Peekskill line stands out sharply on the researchers’ earthquake map, with small events clustered along its length, and to its immediate southwest. Just to the north, there are no quakes, indicating that it represents some kind of underground boundary. It is parallel to the other faults beginning at 125th Street, so the researchers believe it is a fault in the same family. Like the others, they say it is probably capable of producing at least a magnitude 6 quake. Furthermore, a mile or so on, it intersects the Ramapo seismic zone.

Sykes said the existence of the Stamford-Peekskill line had been suggested before, because the Hudson takes a sudden unexplained bend just ot the north of Indian Point, and definite traces of an old