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 to regulate water supply and use. Tourism and recreation are major industries on the Great Lakes. A few small cruise ships operate on the Great Lakes including a couple of sailing ships. Sport fishing, commercial fishing, and Native American fishing represent a U.S.$4 billion a year industry with salmon, whitefish, smelt, lake trout, bass and walleye being major catches. Many other water sports are practiced on the lakes such as yachting, sea kayaking, diving, kitesurfing, powerboating, and lake surfing. The Great Lakes Circle Tour is a designated scenic road system connecting all of the Great Lakes and the Saint Lawrence