The Enid News and Eagle, Enid, OK

November 12, 2013

Earthquakes roll across Oklahoma in recent days

By Dale Denwalt, Staff Writer
Enid News & Eagle

ENID, Okla. — In central Oklahoma, among the small towns surrounding the state’s capital, earthquakes have become more common than tornadoes.

Every few days, it seems the ground shakes at least once somewhere, lighting up the news media with reports of magnitude 3 and 2 quakes — considered puny compared with those along the Californian San Andreas fault.

Those small towns get a lot of the attention, said research seismologist Austin Holland, but he’s more interested in what’s going on around Enid.

Enid and area residents react night of the quake and on social media

Oklahoma used to be a place where earthquakes were someone else’s problem; now, though, it’s become more common for someone in central or northern Oklahoma to describe what it feels like when the ground starts to move.

That, and Holland said Okies feel a different earthquake than those along the West Coast. Here, it usually starts with a “boom.” That’s because the sound waves caused by the earthquake don’t dissipate and instead hit at the same time as the physical shaking.

“The rock in Oklahoma hasn’t been as chewed up, so the seismic waves travel a little bit faster. When it interacts, it can lose some of its energy,” he said. “We’re not losing as much energy as waves radiate out from the earthquake.”

To the state’s top seismologist, the activity occurring north of Enid is more interesting than what’s going on closer to Oklahoma City.

“The actual increase up there has been more startling and dramatic than what’s going on near Oklahoma City,” Holland said.

On Monday, a 3.4-magnitude temblor originated near Kremlin, the strongest so far this year in Garfield County. Mike Honigsberg, certified director of Enid/Garfield County Emergency Management, said no damage was reported.

In Oklahoma, seismologists usually wait to expect damage following 4.5-magnitude earthquakes, although it’s not guaranteed. The lowest-magnitude quake in Oklahoma that caused reported damage was just a 3.4.

Because the earthquakes here are faster and aren’t dissipated by other fractures, the potential for damage appears at lower-magnitude earthquakes. Typically, the benchmark for a damaging quake elsewhere is magnitude 5. Most of Oklahoma’s are “tiny and rare,” Holland said, adding there are plenty of faults in the Sooner State.

“It doesn’t take a San Andreas fault that runs hundreds of miles to create small earthquakes,” he said.

Holland isn’t the only earthquake scientist fascinated by the Oklahoma earthquake phenomenon. His colleagues from around the country rib him about it.

“They’ve accused me of stealing their earthquakes because things have been more quiet than normal,” he said. “A lot of people around the country are puzzled and intrigued by what’s going on, as am I.”

Atypical earthquake activity has occurred near Oklahoma City since 2009, but the Enid-area quakes have only cropped up in the past six months to a year.

“It’s of great interest to us,” Holland said.

It’s of so much interest, Oklahoma Geological Survey installed another seismometer in the rural back country near Carrier. OGS has applied for several grants to continue studying the uptick in earthquakes, and Holland guaranteed his research team would be making more trips to the area.

He expects more, but that’s as far as his predictive powers go.

“Whether they’re going to be big or small, I have no way to know,” Holland said.

It’s also hard to pin down a specific cause of Oklahoma’s newest claim to fame. It could be injection wells tied to the oil and natural gas industry, he said. In other cases, it could be because Lake Arcadia in northeast Oklahoma City has undergone major stress over the past year, Holland told KWTV last week.

Part of his planned research is to examine whether the energy industry’s use of disposal wells, also known as injection wells, causes enough stress along Oklahoma’s faults and fractures to make them slip.

“This is an area where there’s a lot of injection occurring in the area,” he said.