Colorado is not known for its seismic activity, but it has experienced some notable earthquakes in its history. The most powerful one occurred over 140 years ago, and it shook the entire state and beyond.
The 1882 Earthquake
On November 7, 1882, at 6:27 p.m., a magnitude 6.6 earthquake struck near the town of Fort Collins, about 65 miles north of Denver. The quake was felt as far away as Salt Lake City, Utah, and Cheyenne, Wyoming. It caused widespread damage to buildings, roads, bridges, and railroads, especially in the northern part of the state. Some of the effects included:
- Cracks in walls, chimneys, and foundations
- Broken windows, dishes, and furniture
- Landslides, rockfalls, and fissures in the ground
- Changes in the flow of springs and wells
- Altered levels of lakes and rivers
- Shaking of trees, crops, and animals
The earthquake also triggered several aftershocks, some of which were felt for weeks after the main event. Fortunately, no fatalities were reported, but some people were injured by falling debris or panicked horses.
The Cause and Impact of the Earthquake
The 1882 earthquake was the result of a sudden movement along a fault in the basement rocks of the Colorado Plateau, a large area of uplifted and eroded land that covers most of western Colorado and parts of Utah, Arizona, and New Mexico. The fault is part of a complex network of fractures that formed during the mountain-building processes that shaped the Rocky Mountains millions of years ago.
The earthquake was a rare and unexpected event, as Colorado is located far from the boundaries of the major tectonic plates that cause most of the world’s earthquakes. However, the region is still subject to stresses from the ongoing deformation of the North American continent, which can occasionally trigger quakes along pre-existing faults.
The 1882 earthquake had a significant impact on the scientific understanding of the geology and seismology of Colorado and the surrounding areas. It was the first large earthquake to be recorded by seismographs in the United States, and it provided valuable data on the location, depth, and magnitude of the quake. It also stimulated interest and research on the seismic hazards and risks in the region, which led to the establishment of the Colorado Earthquake Information Center in 1972.
The Future of Earthquakes in Colorado
Colorado is still considered a low-to-moderate seismic risk area, but it is not immune to future earthquakes. According to the U.S. Geological Survey, there is a 5% chance of a magnitude 6 or greater earthquake occurring in Colorado in the next 100 years. The most likely sources of such quakes are the faults in the western part of the state, where most of the historical seismicity has occurred.
However, there is also a possibility of induced seismicity, or earthquakes caused by human activities, such as mining, fracking, or injecting fluids into the ground. Some of these activities have been linked to small-to-moderate quakes in Colorado in recent years, such as the 2011 magnitude 5.3 quake near Trinidad, which was the largest since 1882.
To prepare for and mitigate the effects of potential earthquakes, Colorado residents and officials should follow the recommendations of the Colorado Geological Survey, which include:
- Educating themselves and others about the earthquake history and hazards in the state
- Participating in the annual Great Colorado ShakeOut, a statewide drill to practice earthquake safety
- Developing and implementing earthquake emergency plans for homes, schools, businesses, and communities
- Retrofitting and strengthening buildings and infrastructure to withstand seismic forces
- Supporting and funding earthquake monitoring and research programs
Conclusion
The 1882 earthquake was the biggest and most damaging earthquake to ever shake Colorado, but it was not the last. Colorado is still vulnerable to natural and human-induced quakes, which could pose a threat to the safety and well-being of its people and environment. Therefore, it is important to be aware of and prepared for the possibility of future seismic events in the state.