Major earthquake in Colorado unlikely but not impossible

US Geological Survey earthquake hazard map for the United States. (USGS)
US Geological Survey earthquake hazard map for the United States. Click for a larger view. (USGS)

Following yesterday’s magnitude 6.0 earthquake in Napa Valley, California and recent, far milder temblors near Greeley, Colorado residents have to wonder if a major earthquake is possible in the Centennial State.

Longtime Denver residents well know that earthquakes here are not unheard of.

From the late 1960s to the early 1980s, small quakes in the Denver area were relatively common.  The majority of those have been attributed to the injection of liquid waste into the Earth out at the Rocky Mountain Arsenal.

Similar manmade processes are believed to be the source of recent earthquake activity in Oklahoma and possibly the earthquakes seen in May and June of this year near Greeley.

Southern Colorado near Trinidad routinely sees small earthquakes.  Some of the activity there may be related to mining.  However the area is also home to the Northern Sangre de Christo Fault and the Southern Sawatch Fault, both of which have been sources of activity in the past.

Looking farther back, it was on November 7, 1882 that the largest known quake in the state’s history occurred.  A temblor estimated at magnitude 6.6 struck near Rocky Mountain National Park.  Contemporary news accounts of the day indicate damage was seen in Boulder and the quake was felt as far away as Salina, Kansas and Salt Lake City, Utah.

The latest hazard outlook from the US Geological Survey (USGS) does show a moderate hazard potential for parts of Colorado, particularly the Western Slope.

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