by Dakin Campbell and Alexander Eule
As the No. 1 train emerges above ground at 122nd Street in northern Manhattan few passengers realize they have just traveled through the path of a geological fluke, an underground fault line that has the potential to shake New York City to its core.
New data from scientists at Columbia’s Lamont-Doherty Earth Observatory, the hub of Northeast seismology research, is now shedding light on the so-called 125th Street fault line. As technology and reporting strategies improve, a theory is emerging to suggest that the fault line may have reactivated and recently caused several small earthquakes in the city, according to Won-Young Kim, a research scientist at Lamont and the principal investigator of the Lamont-Doherty Cooperative Seismographic Network.
While the city does not sit on a major fault like the notorious San Andreas in California, the East Coast has never been immune from earthquakes. While Kim does not expect the 125th Street fault to produce major earthquakes, its tremors have been noticed by New Yorkers across the city. The fault carries its name because early New York engineers, likely unaware of the geology, built 125th Street through the small valley created by the fault.
Among Kim’s findings are that New Yorkers have a much higher sensitivity for earthquakes than California residents. In December 2004, New Yorkers called police after a series of four earthquakes registering less than 1 on the Richter scale shook city neighborhoods.
“Here we have about one magnitude higher in terms of sensitivity,” Kim said, comparing New York to California. “The people have become very attentive of their surroundings these days. After 9/11, if they feel anything they call.”
Unlike California earthquakes, which stem from the collision of plates at the San Andreas Fault, the smaller 125th Street fault is not the result of any intersection of plates. In fact, New York sits squarely in the middle of the plate between the San Andreas Fault and the mid-Atlantic Ridge, which lies beneath the Atlantic Ocean. The New York fault is activated when plate movement thousands of miles to the east and west compress the 125th Street line.
New York City faced its last significant quake in 1884, when a magnitude 5.2 event off the shore of Far Rockaway, Queens, caused chimneys to fall. That quake was felt from Virginia to Maine. While such a quake is likely to occur every 100 years in New York, scientists believe, the last 120 years have featured smaller earthquakes, including two magnitude 2 events in the fall of 2001 that were felt throughout Manhattan, Queens and Brooklyn.
Kim says his research indicates that these 2001 quakes stemmed from the once dormant 125th Street fault. Meanwhile, Kim says another moderate earthquake similar to the 1884 event is still possible.
Last year, a group of scientists and engineers called the New York City Area Consortium for Earthquake Loss Mitigation issued a report that outlined the potential risk and consequences of another 1884-type event. In New York City, “catastrophic events with Magnitudes 6 and larger are possibilities,” the report states. The group estimates that a moderate magnitude 6 quake at 2 p.m. would cause 1,170 deaths and close to $40 billion in damages.
Those are worst-case scenarios, however. “The object of the study was not to introduce any type of panic,” says George Deodatis, a civil engineer who was part of the consortium. “People in New York have higher priorities.”
“The odds are that it won’t happen in our lifetime,” says Tom Giordano, a planner in the preparedness unit of the New Jersey Office of Emergency Management. “But we still need to do things to prepare for it.”