Minnesota has been the most seismically active in the region of Minnesota , Wisconsin , Michigan 's Upper Peninsula and southern Ontario . Several earthquakes have been documented in Minnesota in the last 120 years , with at least six in the GLTZ . The epicenters show a clear relationship to tectonic features of the state ; four epicenters lie along the Great Lakes tectonic zone . Depths are estimated at . The best-documented event occurred on July 9 , 1975 , near Morris , Minnesota , with a magnitude of 4.6 , and a felt area of covering parts of four states
Morris , Minnesota
1975 Morris earthquake
Great Lakes tectonic zone