Ground-Truthing after M4.0 - EQ

Maine and adjacent states, showing locations of historical M≥4.0 earthquakes since 1638. Orange dots, historical earthquakes (1638–1974); blue dots, instrumentally located earthquakes (1975–present). Earthquake data for 1638–1990 from Ebel (1990); earthquake locations and magnitudes for 1990–present from the Canadian National Seismic Network (Natural Resources Canada, 2013). Number in parentheses following magnitude is number of earthquakes of that size on map. Red star, location of southern Maine earthquake of October 16, 2012.