A magnitude 3.7 earthquake was recorded Tuesday in the Paradox Valley about 4 miles south of Bedrock, according to the U.S. Geological Survey and University of Utah Seismograph Stations.
It was recorded at 3:53 p.m. Tuesday and originated 0.2 mile below the surface.
A magnitude 3.8 quake occurred in the same area Nov. 8 at 4:19 a.m. and was followed by 2.2 and 2.7 aftershocks about two hours later.
Bedrock is about 17 miles east of La Sal, Utah.
No reports of damage have followed the recent quakes in the area.
“Damaging earthquakes are rare in the western Paradox Basin,” USGS said, adding that the largest quakes were a magnitude 4.4 quake in 2000 near the Paradox Valley. That quake and smaller earthquakes in the area were attributed to the injection of brine in deep wells and the nearby brine injection well of the Paradox Valley Salinity Control Facility, said Jim Pechmann, a seismologist with the University of Utah Seismograph Stations.
“It’s pretty likely it was induced from the saltwater injections,” he told The Journal in November.
On March 4, 2019, a local-record 4.5 magnitude earthquake hit in the same area of the injection well, and there were multiple aftershocks. It was also linked to the brine injection facility by seismologists. That quake was felt in Moab, Dove Creek, Cortez and Towaoc.
After the 2019 earthquake, the Bureau of Reclamation salination injection well facility temporarily shut down for study about well capacity and the earthquakes. The plant intercepts salty groundwater draining into the Dolores River and injects it 2.9 miles underground to improve water quality in the Dolores River and Colorado River.
But an unintended consequence of pumping briny fluid deep underground has been thousands of human-induced earthquakes.
In April, the plant was restarted, and injection volumes were reduced by a third with the hope that reduce pressure and volume would avoid induced earthquakes.
“The system worked well for a good long time, but there is a limit on how much water you can pump down there,” Pechmann said. “It looks like the fluid has run into a barrier, and is not diffusing away from the well, building up pressure.”
A total of 10 earthquakes of magnitude 3.0 or greater have occurred within 15 miles of the epicenter of Tuesday’s quake since 1997.
