GREEN RIVER –– The area west of Green River has seen an increase in small earthquakes during the past two years, but there isn’t cause for alarm according to a University of Wyoming geologist.
In the past 30 days, four earthquakes have been reported near Little America, each registering around 3.0 on the Richter scale according to USGS data. The mort recent was two kilometers northwest of Little America, reported Sunday at 3:35 p.m. The quakes range in depth between 2.3 and 3 kilometers.
Joe Biasi, assistant professor of economic geology at UW, said there has been an increase in earthquakes with a magnitude of approximately 3.0 near Sweetwater County’s trona patch, but notes those earthquakes have minimal effect on buildings or the earth’s surface. Biasi said the small quakes are likely attributed to increased activity in the mines, saying earthquakes of similar magnitude can be caused when a quarry or coal mine blasts off a fresh rock face.
“The Powder River Basin in eastern Wyoming has had hundreds of similar blasting-related quakes over the last five years,” he wrote in an email to SweetwaterNOW.
However, Biasi also notes trona doesn’t normally require explosives to mine because it is a soft material. He said one of the trona mines may have run into tougher rock that requires explosives to get through, though he isn’t certain if that is the case.
SweetwaterNOW reached out to the area’s trona mines to inquire about possible blasting, with Tata Chemicals saying it doesn’t use explosives in its mining operations. Genesis-Alkali said it is monitoring the activity.
“As you know, it is common to have seismic activity in the mountain west. We are closely monitoring this activity. We have contracted with an outside technical firm who has geotechnical and rock mechanics experience with our mine and the region to assist with review of historical seismic activity and current low level seismic activity,” Genesis-Alkali HR Manager Jamie Monagle, wrote in an email to SweetwaterNOW.
Regardless of how they’re starting, Biasi says there isn’t anything to worry about and the smaller quakes won’t trigger something larger.
“There is no cause for concern at the moment. This area is not very geologically active and these small quakes are not going to trigger a larger one,” Biasi wrote.
