Seismologists to Study Colorado Earthquakes

A research team from the U.S. Geological Survey plans to visit the Las Animas County area around Trinidad, Colo., to study a recent series of minor earthquakes, which in the past have been blamed on wastewater injection wells from drilling projects.

Seismologists said there were three earthquakes Wednesday and four more this month. The strongest was a magnitude of 3.6. There have been no reports of injury or damage from the quakes.

Justin Rubinstein of the USGS said five of the recent quakes were at least a magnitude of 2.5 and need to be studied. He said the average number of quakes above magnitude 3 in the area has risen from twice a year to eight a year since August 2001.

“The majority of (activity) appears to be related to industrial activities in the area, specifically, the deep injection of large volumes of wastewater appears to be making earthquakes more likely,” he said.

“This level of (seismic activity) is not out of the ordinary for the Trinidad area,” he said. “That said, the level (of magnitude) was much lower than it is now.”

Rubinstein plans to lead a research team of seismologists from the USGS offices in Colorado and California to study the trend. He didn’t say when that will happen.

Residents of Trinidad and Las Animas County have mixed emotions about the earthquake trend. Many say they never notice the temblors and aren’t concerned, while others wonder if it could lead to bigger earthquakes.

The same area had a magnitude 5.3 quake in August 2011 that damaged several buildings. Experts say it was the state’s largest natural quake in more than a century.

“The mortar in some of the downtown brick buildings is more than 100 years old,” said resident Terry Sears. “Some of them shifted during the last strong quake. It wouldn’t take one much stronger than that to bring down some of those buildings.”

Kim Chavez, the county’s emergency manager, said a disaster plan is in place, just in case the area suffers a major earthquake.

“I just worry if we’re going to have a huge one, and we’re not going to know how to react to it,” she said. “We can have every emergency plan available, but it’s when it actually plays out, to see if it’s going to work.”