Oklahoma has never been known as earthquake country, with a yearly average of about 50 tremors, almost all of them minor. But in the past three years, the state has had thousands of quakes. This year has been the most active, with more than 2,600 so far, including 87 last week.
While most have been too slight to be felt, some, like the quake on Saturday and a smaller one in November that cracked a bathroom wall in Ms. Sexton’s house, have been sensed over a wide area and caused damage. In 2011, a magnitude 5.6 quake — the biggest ever recorded in the state — injured two people and severely damaged more than a dozen homes, some beyond repair.
State officials say they are concerned, and residents accustomed to tornadoes and hail are now talking about buying earthquake insurance.
“I’m scared there’s going to be a bigger one,” Ms. Sexton said.
Just as unsettling in a state where more than 340,000 jobs are tied to the oil and gas industry is what scientists say may be causing many of the quakes: the widespread industry practice of disposing of billions of gallons of wastewater that is produced along with oil and gas, by injecting it under pressure into wells that reach permeable rock formations.
“Disposal wells pose the biggest risk,” said Austin Holland, a seismologist with the Oklahoma Geological Survey, who is studying the various clusters of quakes around the state.