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
Great Lakes Megalopolis Great Lakes Megalopolis The Great Lakes Megalopolis consists of the group of metropolitan areas in North America largely in the Great Lakes region and along the Saint Lawrence Seaway. To its south and west, it lies in the Midwestern United States, extending east into western Pennsylvania and Upstate New York, as well as north to Southern Ontario and the southern part of Quebec in Canada. It is the largest and most populated megalopolis in North America. At its most inclusive, the region cuts a wide swath from the Twin Cities in Minnesota to Pittsburgh, Pennsylvania and Rochester, New York. On