By Jessica Miller, Staff Writer
Enid News and Eagle
MEDFORD, Okla. —
Earthquakes in Grant County have some residents speculating about possible causes for the temblors that are becoming commonplace.
“We definitely can feel them up here,” Medford City Manager Dea Mandevill said. “A lot of the time you can hear them. You can hear them coming. And then your house will rattle just a little bit and you will know that’s what it was.”
Five earthquakes rattled the area between Saturday and Monday, according to U.S. Geological Survey. A 2.7-magnitude earthquake was reported 6 miles east of Medford at 10:40 a.m. Monday. There were four earthquakes recorded in the Medford area Saturday, ranging from 2.5 to 3.3 magnitude.
Mandevill said the quakes began occurring on a regular basis six to nine months ago.
“I think, anymore, people are like, ‘Oh, another earthquake.’ No one’s really scared ... it’s just they’re getting so common anymore. They’re just a little shake,” Mandevill said.
Jim Shepherd, deputy emergency manager for the city of Medford, has felt several of the tremors and has an app on his phone to confirm the sounds are indeed earthquakes.
“It’s getting to be a regular occurrence it seems like,” he said.
Robert Moss, who lives seven miles east of Medford, felt one of the earthquakes Saturday.
“It actually shook our porch on the house pretty good,” he said, adding he was outside planting some flowers at around 2:30 p.m. when the earthquake occurred.
Moss is not concerned about the earthquakes.
“(I’m) just more curious. It seems kind of different that we’re having these things, one every other week or so,” he said. “Maybe the earth is just settling.”
Mandevill said officials do not know what is causing the tremors.
“Speculation is all the oil activity, but nothing’s been confirmed,” she said.
Grant County District 1 Commissioner Max Hess said he also had heard speculation the quakes are being caused by “the fracking of the wells.”
Hess felt an earthquake a few weeks ago but did not feel the more recent ones.
“It was a noise, you know how when a plane flies over,” he said. “It made a rumble and then it was loud and then it was over with.
“I’m surprised that we’re having more and more of them. I don’t understand why.”
Robert Williams, a geophysicist with U.S. Geological Survey, said there has been an increase in earthquakes in north-central Oklahoma over the past six to eight months. He said there also have been a few earthquakes in south-central Kansas.
“We do know that the region up in north-central Oklahoma is an area that has seen a large increase in oil and gas activities over the last couple of years, so we’re looking at the possibility of water injection as being a contributing factor to the cause of the earthquakes,” Williams said.
He said when water is injected into the earth’s surface, it can lubricate the faults and make them easier to slip or change the stress conditions.
“It’s something that scientists are considering. But understanding the root cause of earthquakes in Oklahoma is not well understood either,” Williams said.
In California, scientists can see the plate boundary between North America and the Pacific and the grinding going on there. He said there’s a good mechanical model to predict that earthquakes will occur.
“But in the interior of the continent, in Oklahoma, the mechanism is not really clear. We do know that the crust of the earth is stressed to the point that earthquakes can occur, we just don’t what the triggers are and the mechanics of how those earthquakes happen,” Williams said.