1882 Fort Collins earthquake
   Fort Collins Denver  Fort Collins | |
| UTC time | 1882-11-08 19:30:00 |
|---|---|
| USGS-ANSS | ComCat |
| Local date | November 8, 1882 |
| Magnitude | Mfa 6.2, Mw 6.6±0.6 |
| Epicenter | 40°30′N 105°30′W / 40.5°N 105.5°W |
| Areas affected | United States of America |
| Max. intensity | MMI VII (Very strong) |
The 1882 Fort Collins earthquake or 1882 Front Range earthquake was a Mw 6.6 earthquake that struck near Fort Collins, Colorado at 1:30 UTC on November 8th, which was 18:30 on the 7th locally. The earthquake occurred as the result of deformation within the Front Range and caused shaking as strong as Modified Mercalli Intensity (MMI) VII (Very Strong). Shaking was felt as far away as Salt Lake City, Utah and Salina, Kansas. An aftershock struck at 4:45 on the 8th local time and was felt as far as Laramie, Wyoming and Meeker, Colorado. It is the largest earthquake in Colorado's history.
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).[1][2]
Earthquake
The Mw 6.6[a] earthquake struck at 1:30 in the morning on November 8th in UTC time, or 18:30 the 7th locally. 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 km2 (180,000 sq mi).[1] Due to the sparseness of the epicentral region, very little is known about where exactly the earthquake occurred.[1] An aftershock of magnitude 4.5 to 5.0 was also felt in the urban corridor.[4] This earthquake is the largest known to have occurred in the state of Colorado.[3]
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.[3]
Notes
Sources
- Kirkham, Robert M.; Rogers, William P. (1986). AN INTERPRETATION OF THE NOVEMBER 7, 1882 COLORADO EARTHQUAKE (Report). doi:10.58783/cgs.of8608.ujor4101. Retrieved 2024-05-04.
- Kirkham, Robert M.; Rogers, William P. (1985). Bulletin 46 - Colorado Earthquake Data and Interpretations 1867-1985 (Report). doi:10.58783/cgs.b46.fdpq8494. Retrieved 2024-05-04.
- Spence, William; Langer, C. J.; Choy, George L. (1 December 1996). "Rare, large earthquakes at the Laramide deformation front—Colorado (1882) and Wyoming (1984)". Bulletin of the Seismological Society of America. 86 (6): 1804–1819. doi:10.1785/BSSA0860061804. Retrieved 4 May 2024.
- Wong, Ivan G.; Humphrey, James R. (1 September 1989). "Contemporary seismicity, faulting, and the state of stress in the Colorado Plateau". Geological Society of America Bulletin. 101 (9): 1127–1146. doi:10.1130/0016-7606(1989)101<1127:CSFATS>2.3.CO;2. Retrieved 4 May 2024.