Pipestone, 28 September 1964

The original reference for this even has been lost and cannot be reconfirmed. The event was located instrumentally. The location (44 degrees N, 96.4 degrees W) places the epicenter 6 km (4 miles) due west of Pipestone, Minnesota, and 4 km (2-1/2 miles) east of the Minnesota-South Dakota border. No felt report exists.

Source: Earthquake History of Minnesota, Harold M. Mooney, Minnesota Geological Survey, University of Minnesota, Saint Paul, 1979