1882 Fort Collins Earthquake
Tectonic setting
The Southern Rocky Mountains are still actively growing due to the Laramide orogeny. The Front Range accommodates some of this as a deformation front of the orogeny. Stresses in this region are generally northwest–southeast oriented. The causative fault of this specific earthquake is unknown, but other earthquakes such as the 1984 Wyoming earthquake struck at a depth of 20 km (12 mi).
Earthquake
The Mw 6.6 earthquake struck at 01:30 on November 8 in UTC time, or 18:30 on November 7. The earthquake caused Modified Mercalli intensity (MMI) VII (Very Strong) shaking in various localities near in the Front Range urban corridor and was felt over an area of 470,000 km (180,000 sq mi). Due to the sparseness of the epicentral region, very little is known about where exactly the earthquake occurred. An aftershock of magnitude 4.5 to 5.0 was also felt in the urban corridor. This earthquake is the largest known to have occurred in the state of Colorado.
Damage
At the University of Colorado Boulder, plaster fell from the ceiling. In Denver, some bolts snapped and bent at an electric light plant. In La Porte, a wooden house suffered cracking. At Thompson, a house's walls were severely cracked and the plaster on some walls came off. Glass windows broke in Laramie.