EARTHQUAKES IN NORTHERN NEW YORK

The earthquakes in northern New York are part of an extension of the Western Quebec seismic zone extending from Western Quebec across the St. Lawrence River into northern New York. The northern New York area is an area of moderate seismicity with many small earthquakes (m<4) caused by thrust faulting along the northwest trending faults. These small earthquakes have foci located in the Precambrian rocks at depths less than 10 kilometers. Three damaging earthquakes have occurred during the past 70 years including the 5.9 magnitude Massena earthquake of 1944, the 5.2 magnitude Goodnow earthquake in 1983 and the most recent 5.3 magnitude Au Sable Forks earthquake in 2002. These earthquakes caused 25,000,000 todays dollars damage in the area. Aftershocks of these earthquakes continue to occur to this day.

Besides the damaging earthquakes, earthquake swarms have occurred at Blue Mountain Lake in 1972 and 1973. In 1986, many earthquakes were induced at an abandoned mine at the Witherbee-Minerville area in the eastern Adirondacks so the Adirondacks continue to be an actively seismic region.

Several hypotheses have been suggested to account for the earthquakes. These include the earthquakes are part of an extension of the Boston-Ottawa seismic zone, glacial rebound, fractures caused by a hotspot, reactivations of old faults and stress concentrations along mafic plutons. Many of the epicenters lie in gravity highs thought to be due to mafic plutons. The earthquakes promote much interest in the seismicity of the region by local residents and provide a source of research activities for students.