118 Geophysics/Tectonophysics/Seismology (Posters)

Tuesday, 29 October 2002
8:00 AM - 12:00 PM

SPATIAL DISTRIBUTION OF EARTHQUAKES IN NORTHEASTERN N. AMERICA

Paper number: 118-4
Program: Technical Sessions
Time: 8:00 AM – 12:00 PM

Authors

Abstract

Analysis of the spatial distribution of earthquakes in the northeastern United States and surrounding Canadian provinces reveals their locations to be concentrated in concentric rings centered about a position offshore of Small Point, Maine. The spacing of these concentric rings of earthquake centers is approximately logarithmic, similar to the ring spacing observed in impact basins. Fault systems, changes in terrain, and lineaments are closely associated with these earthquake concentration rings. This pattern of earthquake clusters and lineaments extends well beyond New England, reaching at least to Niagara falls and the Maryland-Virginia border.

The earthquake zones are not continuous within a ring, nor are all earthquakes associated with the rings. Earthquakes in the western Quebec seismic zone form diffuse linear groupings oriented radially outward from the center of the concentric ring pattern, crossing several rings. The Charlevoix crater, which is notorious for localizing earthquakes, is itself within one of the concentric rings. The statistical correlation demonstrated in this analysis between the earthquake clusters and the concentric circular rings in the New England region is strong, durable and produces a single, unique center.