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
Summit Lakes (Ontario) creek inflow at the northeast tip. The primary outflow is an unnamed creek, from the south end of the south lake, to Upper Twin Lake, which eventually flows via Rabbit Creek, Rabbit Lake, the Matabitchuan River, Lake Timiskaming, and the Ottawa River into the St. Lawrence River. Summit Lakes (Ontario) The Summit Lakes are a pair of lakes connected by a short creek in Nipissing District, Ontario, Canada, about southeast of the community of Temagami. The Ontario Northland Railway mainline crosses the southern tip of the south lake on a trestle. The north lake is about long and wide, and