Scientist finds possible cause of 5.6 Oklahoma earthquake in November 2011

TULSA - For months we've been looking into a large earthquake that shook the state this past November.

Scientists shared new information with us about its possible cause.

While thousands of earthquakes were being tracked in Lincoln County last year, thousands of gallons of wastewater were being injected into wells nearby.

Once water is used to help get oil and gas out of a rock, that water is later disposed of and goes into an injection well a mile or more deep. In Lincoln County alone there are almost 200 injection wells, that's where a 5.6 quake shook the state in November.

"There are three injection wells that are located within five kilometers (3.1 miles) of the main shock," said Dr. Steve Horton for the Center for Earthquake Research and Information.

2NEWS sent Dr. Horton injection well reports we obtained from the Oklahoma Corporation Commission.

Those reports show how much fluid is pumped into the wells on a regular basis. Horton looked at the 2010 data and the seismic activity in the area and found, "It's possible that the magnitude 5.6 was actually triggered by fluid injection," said Horton.

He recently presented his findings at the Seismological Society of America conference in San Diego, where scientists from across the county share their research, including Austin Holland, with the Oklahoma Geological Survey. He's also the state expert on earthquakes.

"I would certainly say that it's possible and we're looking into it, but at the moment the data is just very inconclusive and really doesn't suggest that. For instance, injection has continued since the earthquakes happened and the earthquakes have decreased dramatically, sort of as we'd expect in a natural process," said Holland.

Horton agrees that it's not conclusive but does believe more research needs to be done.

Meanwhile, Horton's colleague Dr. Bill Ellsworth, with the US Geological Survey, looked at man-made seismic activity across the central U.S. and is particularly interested in the increase in activity in Oklahoma, especially given the number of injection wells in the Sooner State.

"I think we're all being very careful to say this earthquake or that earthquake has been triggered, but it's a question that we need to go back now and look at where the earthquakes are and to try to understand what industrial activities might be in their vicinity to see if there's a link," said Ellsworth.

The Oklahoma Corporation Commission oversees injections in the state and has said in the past that it turns to Holland as its expert, but state representative Ron Peters wants all findings to be looked studied.

"The Corporation Commission could certainly call hearings and hear from all sides of the issue and make some decision based on that," said Representative Ron Peters, (R)-Tulsa.

While Peters says he's inclined to go with Oklahoma's expert, he told us he'll encourage the Commission to allow other experts to weigh in.

After all, Ellsworth says we're all after the same thing.

"This is a challenge for the regulators as to how they want to move forward. I think everyone is interested in developing systems that can produce this really valuable resource in a safe manner," said Ellsworth.

The Oklahoma Independent Petroleum Association has said it doesn't believe the injection wells are tied to the earthquakes and admits any moratorium on injection wells could hurt the oil industry.

Still Holland says it's something he's continuing to look into.

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