Days after a U.S. Geological Survey report indicated state regulatory actions on wastewater injection wells appeared to be working in reducing large earthquakes in northern Oklahoma, Pawnee and Payne Counties were rattled by quakes Sunday night and Monday morning.
The 3.9 magnitude quake, with an epicenter east of Pawnee was recorded at 9:22 p.m. and resulted in no immediate reports of damage. But it was strong enough to be felt in Wichita, Kansas. It’s epicenter was nearly 9 miles east of Pawnee and at a depth of nearly 3 miles, according to the U.S. Geological Center.
Hours later at 2:58 a.m. on Monday, a 3.6 magnitude earthquake was recorded near Cushing in Payne County. Its epicenter was reported to be located about 3 miles north of the city.
It was last week when a new earthquake study of the injection well-induced quakes suggested the cutbacks in injection-well operations should significantly decrease the probability of a larger, damaging quake in 2017 and that Oklahoma should return to tectonic levels within the next few years.
The authors also felt the chance of anything greater than a magnitude-5.0 quake was 37 percent. They further indicated that aftershock sequences linked to the large quakes near Fairview and Cherokee last year and early this year would delay the seismicity rate in those areas.
“Our model predicts that earthquakes in Oklahoma will return to tectonic background levels,” according to the study by scientists Cornelius Langenbruch and Mark Zoback at Stanford University. “However, the occurrence of potentially damaging earthquakes cannot be ruled out during the next few years.”
Their study was published in Science Advances.