Earthquakes, Faults, and Nuclear Power Plants in Southern New York and Northern New Jersey

Abstract

Seismic activity in the greater New York City area is concentrated along several northeast-trending faults of which the Ramapo fault appears to be the most active. Three nuclear power plants at Indian Point, New York, are situated close to the Ramapo fault. For a reactor site in use for 40 years, the probability that the site will experience an intensity equal to or in excess of the design (safe shutdown) earthquake is estimated to be about 5 to 11 percent.

The Giles County, Virginia, seismic zone– Seismological results and geological interpretations

“…At least some faults formed by reactivation of older faults (Ratcliffe, 1971). Near New York City, Aggarwal and Sykes (1978) inferred that some such Mesozoic faults are seismically active, although Ratcliffe (1981a, b, c) questioned that inference.…”

Seismicity in the Area Surrounding Two Mesozoic Rift Basins in the Northeastern United States

“…The seismicity resulting from this type of process would not be expected to be stationary. Some examples of well-known hypotheses that were invoked in the 1970s to explain NEUS earthquakes were the existence of a so-called Boston-Ottawa Seismic Zone (e.g., Diment et al, 1972;Sbar and Sykes, 1973), the hypothesis that NEUS earthquakes are associated with plutons (e.g., Simmons et al, 1976), and the hypothesis that seismic activity in this area is concentrated along NE trending faults, of which the Ramapo fault appeared to be the most active (Aggarwal and Sykes, 1978). We will address each of these in turn.…”

“…The Ramapo fault is a Mesozoic border fault, which forms the northwestern margin of the Newark rift basin (NRB), and which was also active during pre-Mesozoic times (e.g., Ratcliffe, 1971;Ratcliffe, 1980). Aggarwal and Sykes (1978) studied locations, depths and focal mechanisms of earthquakes in the greater NYC area and concluded that seismic activity in this area is concentrated along northeast trending faults, of which the Ramapo fault appeared to be the most active. More recent studies of this area, however, produced results suggesting a more complicated relationship between earthquakes and geological features.…”

A Note on the Geometric Configuration of Seismogenic Zones

“…An earlier microearthquake, located approximately 3 km north of the Verplanck sequence, was interpreted by Aggarwal and Sykes (1978) and Yang and Aggarwal (1981) to be the result of reverse faulting on a northeasterly striking branch of the Ramapo fault in response to a west-northwesterly directed maximum horizontal compressive stress. This event occurred on September 22, 1976, and is referred to as the Indian Point earthquake by Yang and Aggarwal (1981).…”