7/8/2012:
The first instrumentally-located earthquake in the history of North Dakota occurred on this date in 1968. Prior to this, North Dakotans had felt earthquakes as early as 1872, although these were centered as far away as Nebraska and Iowa. The quake of July 8, 1968, was centered near Huff, North Dakota, and was measured at 4.4 on the Richter Scale. Its intensity, however, did not exceed a four on the Mercalli Scale, meaning not everyone would even notice the quake. Although a large area of south-central North Dakota experienced the quake, most people didn’t realize what they experienced. Some reported a sound like thunder. In Huff itself, the noted effect was that a television set had moved.
Dakota Datebook written Jayme Job
Sources:
http://earthquake.usgs.gov/learn/topics/mercalli.php
http://earthquake.usgs.gov/earthquakes/states/north_dakota/history.php