Great Lakes tectonic zone 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. Wisconsin has had no earthquakes along the GLTZ, Michigan's Upper Peninsula has had four earthquakes in the vicinity of the GLTZ – Negaunee, Newberry and two in
Four Mile Lake (Ontario) Four Mile Lake (Ontario) Four Mile Lake is a lake in the city of Kawartha Lakes in Central Ontario, Canada. The lake is northeast of Coboconk, Ontario and west of Burnt River. It is one of the Kawartha Lakes series of lakes and is in the Great Lakes Basin. Four Mile Lake is a relatively shallow warm water lake with a surface area of . The lake is located in the sub watershed of Corben Creek and has a flushing rate of approximately five years. The lake is located on the boundary between two different geological land forms. The northern