Central Oklahoma region is “Earthquake Central”

Loud, booming earthquakes continue to rattle homes and nerves across Oklahoma on an almost daily basis, according to the Oklahoma Geological Survey.

The agency tracking seismic activity in Oklahoma reported more than 20 quakes Saturday. The United States Geological Survey, the national agency that reports on the largest quakes in country and abroad, reported a 3.5-magnitude quake last week in the Edmond area.

Many of the quakes in the latest swarm are centered near Liberty Lake in Logan County.

Nancy York lives in the area. Her tile floor, her ceiling and her walls were all damaged. She said the new cracks in her newly built home were caused by the constant quakes. Not only did York feel eight tremblers Friday, she heard them.

“Felt like bombs going off. It’s just a huge loud noise and then it’s like a reverb from that boom that just shakes the entire house,” York said.

 “When you are on top of a small earthquake it generates a boom. It’s kind of similar to an explosion,” said seismologist Austin Holland with OGS.

Holland said P waves, or sound waves, travel from deep in the earth before erupting at the surface. Although the sound can be powerful, shaking can be minimal.

“I know these booms have been reported in other places and they couldn’t figure out what was going on. The earthquakes were actually too small to detect,” Holland said.

There have been reports of unexplained booms in Indiana, South Carolina, Ohio, Rhode Island and Oklahoma in the last month. All are close to active areas on the USGS seismic hazard map.

“We have a lot of pre-existing faults in Oklahoma,” Holland said.

It appears the faults have become more active.

Since January 2009, more than 200 magnitude 3.0 or greater earthquakes have rattled central Oklahoma, marking a significant rise in the frequency of these seismic events, according to a joint statement by both USGS and OGS.

Studies show one to three magnitude 3.0 earthquakes or larger occurred yearly from 1975 to 2008, while the average grew to around 40 earthquakes per year from 2009 to mid-2013.

Holland said the increase in frequency of earthquakes could just be a natural occurrence or it could be triggered by human activity.

“We’ve looked at hydraulic fracturing,” he said. “I don’t think there’s any question that fracking is one of the causes that led to an unprecedented increase in quakes in this area. Just a few years ago, the area around DFW (Airport) was experiencing frequent earthquakes. It all happened during the time fracking was going on. When the fracking stopped, the earthquakes stopped. You do the logic.”

He said changing lake levels may be playing some role as well. All possible factors are being looked at.

The USGS and OGS are currently conducting collaborative research quantifying the changes in earthquake rate in the Oklahoma City region.

“If I’m experiencing eight of these in one day, then when does it erupt and become absolutely horrible that takes my house down?” York asked. “We have no way to predict the future. Earthquakes aren’t predictable. Certainly the more earthquakes we have, the more likely we are to have a larger one,” Holland said.