More annoying than threatening, tiny tremors are shaking portions of central Oklahoma with increasing frequency – rattling homes, knocking things over and interrupting sleep.
“I feel them every time,” said Luther resident Felicia Bennett. One day last week, “I felt three. It woke me up. The house shaking. Sometimes I hear it popping. Occasionally something will fall. Not often.”
No fewer than 16 small earthquakes were recorded in and around Arcadia and Luther during the past week, including 10 on Tuesday alone, according to the U.S. Geological Survey. The quakes ranged from magnitude 2.8 to 4.3.
“This is something new,” Luther Mayor Cecelia Taft said. “We never had anything. Now all of a sudden, it’s just hitting us.
“The last couple of years, they’ve been getting just terrible,” the lifelong Luther resident said.
About 11/2 years ago, a series of quakes were centered near Sparks, east of Luther. A magnitude 5.6 temblor on Nov. 5, 2011, was the strongest one ever recorded in the state and was preceded by a 4.7 magnitude foreshock and aftershocks of 4.0. The stronger quake was felt in 14 states, buckled highways, damaged a spire at St. Gregory’s University in Shawnee and damaged more than a dozen homes.
In the northeastern Oklahoma County swarm, the quakes are strong enough to be felt but light enough to avoid causing damage.
“Just small shakes. Here at the store, just little tremors,” said Steve Shaw, who lives between Arcadia and Luther and operates a hardware store at Luther. His customers have reported pictures shaking on their walls and things being thrown off tables by the small earthquakes, but none have bought up building materials to repair damaged roofs or floors.
“So far, I haven’t heard of any actual damage,” Shaw said.
State Rep. Lewis Moore, R-Arcadia, said he was awakened by an earthquake about 2 a.m. Tuesday morning “that sounded like a plane crashed in our back yard.”
“I expected there to be damage in Luther. There’s a lot of old buildings there. But I have not heard from anybody,” Moore said.
The Oklahoma Geological Survey said the 2011 quake occurred along the Wilzetta Fault, also known as the Seminole Uplift, a 55-mile-long fault zone that runs from western Creek County to central Pottawatomie County. A study released last month by geophysicists at the University of Oklahoma, Columbia University and the USGS said the earthquake was probably caused when oil drilling waste was pushed deep underground, which would make it the most powerful quake to be blamed on deep injections of wastewater.
But not everyone agrees. Dr. G. Randy Keller, a geophysicist and director of the Oklahoma Geological Survey, said the cause of central Oklahoma’s earthquake Swarm remains a mystery.
“I’d like nothing better than to tell you we have it all figured out. Unfortunately, that’s not the case,” Keller said.
While oil and natural gas exploration could contribute to the region’s seismic activity, “we just can’t conclude that,” Keller said.
“There lots of reasons to believe that this is a perfectly natural earthquake,” Keller said. “You can go either way on that. Frankly, it’s kind of frustrating.”
A.B. Wade, a press officer with the USGS, said in an email that USGS scientists believe it is too soon to have completed an analysis to determine whether there is an association with the central Oklahoma earthquakes and oil and gas exploration.
Keller said his agency has deployed an additional 30 seismographic detection instruments in the region to try to determine the cause of the area’s frequent earthquakes.
“We just have them spread all over the state,” he said.
While the cause of the earthquakes is debated, a number of residents have added earthquake coverage to their insurance policies.
Taft said while she has no idea what is causing the earthquakes, she is urging her constituents to protect themselves and hang on.
“That’s all we can do,” she said.