Whose Fault is it Anyway?

Today is National Richter Scale Day, which honors the birth of Charles F. Richter, the inventor of the Richter Scale. This scale is a quantitative measure of an earthquake’s magnitude (size), devised in 1935. So why are we talking about earthquakes in Colorado? We don’t experience earthquakes, right?

In truth, Colorado does have natural earthquakes and several potentially active faults capable of causing earthquakes as large as a magnitude between 6.5-7.5 according to the Colorado Geological Survey. The largest known earthquake in Colorado happened on November 7, 1882 at a magnitude of 6.6. Another earthquake, though not as large, was more economically devastating. This earthquake, centered near Commerce City, caused more than a million dollars of damage in Denver and the northern suburbs. It took place on August 9, 1967 and registered as a magnitude 4.8. It was followed by a magnitude 4.5 earthquake in November 1967. The cause of these earthquake was thought to be from the disposal of liquid waste into a 12,000 foot well drilled at the Rocky Mountain Arsenal, northeast of Denver. This removal process set off a series of quakes; many too small to be felt by residents. According to an article in the Cañon City Daily Record on October 18, 1989, the liquid lubricated the rocks enough that they slipped and released stress.

Fremont County and other surrounding counties have had their own experiences with earthquakes though none have caused significant damage. An article on March 18, 1985 reported on an earthquake that took place in Salida. It registered as a 3.2 magnitude and no damage or injuries were reported. Another rare quake was reported in southern Colorado (including Fremont County) in December 1995. According to the Cañon City Daily Record on December 26, 1995, the quake registered as a magnitude 3.6 and was centered 10 miles southwest of Colorado Springs. The quake only lasted between 3-5 seconds.

In 2008, another quake was felt by Cotopaxi residents. It had enough energy to be felt, but no damage was caused. It registered as a 3.1 magnitude and occurred at about 8:45 pm on January 25. One resident called the sheriff to clarify it wasn’t a plane crash or something similar after checking with his neighbors that they also felt it.

Despite these occurrences, earthquakes are still rare in Colorado and are only occasionally felt. However rare they are, it doesn’t hurt to have the facts!

The information presented in this article is compiled using research conducted by the Royal Gorge Regional Museum and History Center.

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