On July 26, 1905 the Keewenaw Peninsula was shaken by an earthquake. It was determined to be a VIII on the Mercalli Scale, which translates on the Richter Scale as being between 5.0-5.9. Chimneys were toppled and plate glass windows were broken in Calumet, and the shocks from the earthquake were sensed as far north as Copper Harbor (50 kilometers) and as far east as Marquette (105 kilometers). (Hobbs, 1911). No wonder that the copper mines refused to descend into the mines for the night shift!
Source: D. Michael Bricker, Seismic Disturbances in Michigan, Circular 14, 1977.
From 1902 to 1909, more than 20 earthquakes rattled the UP. Discover more fascinating accounts and events in the book “Forgotten Tales of Michigan’s Upper Peninsula” by Lisa Thiel, available via interlibrary loan from the Library of Michigan.