In 2008, researchers from Columbia University's Lamont-Doherty Earth Observatory located a previously unknown active seismic zone running from Stamford, Connecticut, to the Hudson Valley town of Peekskill, New York—the intersection of the Stamford-Peekskill line with the well-known Ramapo Fault—which passes less than a mile north of the Indian Point nuclear power plant. The Ramapo Fault is the longest fault in the North-East, but scientists dispute how active this roughly two-hundred-million-year-old fault really is. Many earthquakes in the state's surprisingly varied seismic history are believed to have occurred on or near it. Visible at ground level, the fault line likely extends as deep as nine miles below the surface.