A 3.9 magnitude earthquake hit the Eastern Plains on Sunday evening, followed on Monday at 8:50 p.m. by a magnitude 3.7 earthquake that struck northwest Colorado in the Craig area, the National Earthquake Information Center in Golden reported.
The earthquake on Sunday shook an area east of the town of Eads in Kiowa County about 20 miles north of Lamar.
“There’s no reason to think the two earthquakes are related, but there’s an awful lot we have left to learn about earthquakes,” according to Dr. Vincent Matthews, director of the Colorado Geological Survey.
The quake Monday evening occurred about 11 miles north of Craig, according to the NEIC in Golden. The tremors could be felt over a sizeable area in northwestern Colorado with more than 130 people reporting to the USGS that they felt it.
Although there are a number of young, mapped faults in Moffat County, this earthquake does not appear to fall on any of them, according to Matthews. The most recent earthquake in the vicinity occurred in 1994 when a magnitude 2.7 struck about five miles to the southeast.
“Northwest Colorado is another part of the state where a lack of monitoring equipment makes it very difficult to detect and locate smaller earthquakes,” said Matthews. “That’s key to understanding the region’s earthquake potential.”
Matthews added that the Colorado Geological Survey, the University of Colorado and the Colorado Earthquake Hazard Mitigation Council are working to obtain funding to retain a temporary seismometer near Maybell that was installed as part of a nationwide National Science Foundation program.
Geologic studies indicate there are about 100 potentially active faults in Colorado and more than 500 earthquake tremors of magnitude 2.5 or higher have occurred in Colorado since 1870. The largest earthquake experienced in Colorado during historic times was a magnitude 6.6 quake that occurred in the northern Front Range in 1882.
The Colorado Geological Survey has several publications on Colorado earthquakes and potentially active faults, and maintains a reference collection on Colorado seismicity that includes reports by consultants or agencies.
A listing of the reports can be viewed at the CGS web site,
http://geosurvey.state.co.us/Default.aspx?tabid=108.
