A federal facility that pumps salty water 14,000 feet into the Earth's crust most likely has something to do with the magnitude 3.9 earthquake that struck the Utah-Colorado border Nov. 6, a federal official told The Associated Press.
The U.S. Bureau of Reclamation facility removes salt from the Dolores River, then pumps 230 gallons of brine per minute into deep wells under Utah's Paradox Valley Area.
While the process is intended to decrease the salt content of the Colorado River downstream, scientists say it also lubricates faults.
The facility has caused thousands of earthquakes in the area since 1991, but most have been too small for people to notice. The 3.9 quake was felt in Grand Junction, about 60 miles away. No damage was reported.
"We have a seismic network set up for measuring and recording any events associated with the injection process, and it appears this earthquake was one probably associated with that process," said Andy Nichols, manager of the federal facility. "Every once in a while there's a large event felt at the surface, and this was one of those events."
The last large earthquake occurred in May 2000, registering 4.3 on the Richter scale. Combined with two significant tremors in 1999, the event led government officials to reduce the amount of brine injected by a third.
Source: The Associated Press