Multiple earthquakes reported in southern Colorado last week
Multiple earthquakes were reported late last week west of Trinidad in southern Colorado and were some of the strongest reported in Colorado in recent years.
Dr. Kyren Bogolub, a seismologist at the Colorado Geological Survey, told the Chieftain the majority of earthquakes reported in Colorado occur in that area, known as the Raton Basin.
Most of the previous earthquakes in the Raton Basin have been because of injections from water, a byproduct from oil and gas activity, Bogolub said. A map from the Colorado Oil and Gas Commission shows over a dozen underground wastewater injection sites within western Las Animas County.
Bogolub noted that earthquakes can sometimes correlate with underground injection, but in other areas, minimal or no earthquakes occur when liquids are injected underground.
The Raton Basin region experienced some earthquakes prior to 1994 when wastewater injection started, according to a 2017 research paper led by Jenny Nakai, but earthquakes in the region increased dramatically a few years after injection started.
Chieftain news partner KRDO News Channel 13 reported no property damage occurred from the recent earthquakes. Several local residents told the station they felt some of the earthquakes, and a business owner in Valdez said one of them woke him up.
A series of earthquakes rattled the Trinidad area in 2011, with the largest shock recorded at 5.3 magnitude. That earthquake resulted in some minor damage to homes and businesses.
The 2011 earthquake was the largest the state had recorded in over four decades. Nakai’s 2017 research paper found that the 2011 quake was from wastewater injection.
Colorado has a history of earthquakes caused by injecting water deep beneath the earth’s surface. Over 1,300 earthquakes reported in the Denver area in the 1960s were linked to underground fluid injection at the Rocky Mountain Arsenal, a former chemical manufacturing facility.
Bogolub said it’s sometimes difficult to determine whether or not an earthquake was “induced” by human-related activities or not, but she estimates a majority of Colorado’s earthquakes are induced.
Colorado is thousands of miles away from the nearest major tectonic plate boundary — for example, the San Andreas fault is the cause of many previous major earthquakes in California. But there are still many faults beneath the surface of the earth, including in Colorado, that geologists have yet to confirm.
“A lot of (faults) have no expression at the surface,” Bogolub said. “The easiest way for us to map geology of any type is by looking at what's on the surface. Anything that's underneath the surface adds a lot of challenges. The techniques that we have for understanding what's going on are limited in what they can do.”
A Colorado Geological Survey website states that the first reported earthquake in Colorado was in eastern Pueblo County near Fort Reynolds in December 1870. Accounts of the earthquake were published in the Pueblo Chieftain, as well as the Denver-based Rocky Mountain News, Colorado Transcript in Golden and the Central City Register.
Since the reported earthquake in 1870, few earthquakes have been reported in Pueblo County, all with a magnitude less than 3. The most recent quake within county limits was a 2.9 magnitude shake in 2016, approximately 14 miles southwest of downtown Pueblo.
Anna Lynn Winfrey is a reporter at the Pueblo Chieftain. She can be reached at awinfrey@gannett.com or on Twitter, @annalynnfrey.
This article originally appeared on The Pueblo Chieftain: Multiple earthquakes reported near Trinidad
