A SEISMIC HAZARD STUDY OF THE MASSENA AREA, NORTHERN NEW YORK

Massena lies along several geologic features that may contribute to its seismic hazard. It lies along an extension of the New England seamount chain that is seismically active. It also lies along a possible extension of the Carthage-Colton Mylonite zone and in the northeast trending Western Quebec seismic zone. Also, it is located in the St. Lawrence Valley Fault Zone and along the Gloucester and Winchester Springs faults that trend through the Massena area. Historic earthquake data from Smith (1966) indicates earthquake activity is persistent over a 400-year period in the area and earthquake monitoring by Lamont-Doherty and Canadian Geological Survey indicates it persists today. No known surface faults are related to the earthquakes, however fault plane solutions indicate reverse faulting on NNW to NW striking planes.

On September 5, 1944, an earthquake of intensity VIII on the Modified Mercalli Scale shook the Massena-Cornwall area. This magnitude six earthquake caused $2,000,000 in damage, mostly to chimneys and cracked brick walls. Studies of the destructive effects of the earthquake with the geology indicated the most destructive effects were found on structures built on the Massena (Leda) clay. This is a marine clay deposited in the Champlain Sea and occurring at Massena, NY, Cornwall, and Ottawa, Canada. Large-scale (1:24,000) maps of the Massena area have been drawn to show the distribution of this clay. The scale of the maps make them practical for residents in the area to determine the location of their houses or structures relative to the clay. Maps of the Ottawa area also show the distribution of the Leda clay.