Twelve earthquakes have been documented in Minnesota in the last 120 yr. The first 9 were felt, whereas the last 3 (all in 1979) were detected instrumentally by a six-element seismic array which has recently been put into operation. Estimated magnitudes range from 0.1 (instrumental only) to 4.8, with four of magnitude 4.3 or greater. The highest intensity values were VI to VII. Depths where obtainable are estimated at 5 ...
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