Seismologist: Cannot Link Drilling To Oklahoma Earthquakes

By Alex Cameron, Oklahoma Impact Team

JONES, Oklahoma -- Oklahomans have proven they can handle most anything Mother Nature can dish out: tornadoes, wildfires, ice storms, flooding. Been there, done that. Residents of one town can now add earthquakes to the list.

The people of Jones and other rural communities in eastern Oklahoma County and western Lincoln County, in the central part of the state, have been experiencing what geologists refer to as an earthquake "swarm" over the past year.

Relative to the temblors that recently struck Haiti and Chile, these quakes have not been very strong -- ranging in magnitude from 1.5 to 3.8, and yet many have been big enough, not only to be felt, but to rattle houses and rattle nerves.

"It was just ka-boom!" said Jenifer Reynolds, describing one of the first tremors she felt at her Jones home last year. "And it shook the windows and shook the house."

Reynolds and her husband, Chris Cook, said they've personally felt about a half a dozen quakes like that -- not strong enough to seriously scare them, but enough to scare their animals.

"Ya know, horses take off running, and dogs are running off the porch, ya know, it's kind of.. of that magnitude, ya know," Reynolds said.

At Shuff's Main Street Grill, a local lunchtime mainstay, the seismic activity is a popular topic of conversation.

"It'll rock ya pretty good," said Vic Walker, a lifelong resident of the area.

And among the patrons, there's no shortage of ideas on what could be causing the earthquakes. They range from the ridiculous to the sublime.

"A bunch of gophers," laughed Buddy Moseley;

"The only theory that I have is that it's a Biblical statement," ventured Buddy's wife, Grace.

A popular theory that's also circulating is that the earthquakes are the result of increased oil and gas drilling in the state.

Rather than speculate on a cause, the Oklahoma Geological Survey is researching the quakes and trying to come up answers, based on facts, and the facts surrounding the seismic swarm are fairly startling:

- between 1977 (when Oklahoma modernized its seismic monitoring system) and 2008, there were a total of 28 earthquakes in Oklahoma and Lincoln Counties; a rate of less than one earthquake per year.

- since the start of 2009, there have been 134 earthquakes recorded in those same counties; a rate of 95 per year.

To make sense of this increase, OGS brought in Austin Holland, a PhD candidate at the University of Arizona and a research seismologist.

For Holland, the first order of business was to get better location data on the quakes, which required that he set up temporary seismic stations in and around the area of seismicity. The U.S. Geological Survey lent him 10 new accelerometers, which have been deployed and whose recordings Holland can access through a link on his computer.

Such a network of seismic monitoring stations and the data they provided were critical in unraveling a similar mystery a year ago in Texas.

On Halloween night, 2008, residents around the Dallas-Fort Worth airport began experiencing a series of tremors -- the first felt earthquakes in that area since 1950. Geologists from Southern Methodist University and the University of Texas were intrigued and decided to take a closer look.

Dr. Brian Stump, a professor Earth Sciences at SMU, said the seismic equipment they put in place showed them something extraordinary about the epicenters of the earthquakes they recorded.

"They all locate in that little square," Stump said, pointing to a spot just south of the Dallas-Fort Worth airport.

And that square, he said, was right along a known fault line, and right next to a wastewater injection well.

Stump and other geologists said production wells have not been tied to earthquakes, but disposal wells, where the saltwater and other fluids used in oil and gas production are injected back into the earth have been shown, in some cases, to cause small quakes.

"Fluids of all kinds, when they're injected underground, do, in some cases, induce small earthquakes," Stump said.

Stump said they also learned that the injection well in question has started putting fluids into the ground just a few weeks before the DFW quakes began.

"And so, as we finished the study," Stump said, "we can't be absolutely sure that's the cause, but the timing and locations and things seem to say at least we should consider that as a possibility."

The resulting peer-reviewed paper got plenty of attention, including Holland's.

"We've looked at the saltwater disposal certainly as a possible theory," Holland said.

By far, the highest volume disposal wells in the area of earthquakes belong to Tulsa-based New Dominion, LLC. They pump, on average, 3.5 million gallons of saltwater a day into the Arbuckle formation, along a fault known as the Nemaha Ridge.

During a visit to their facilities recently, we asked if they thought they could be causing earthquakes.

"Well, we didn't think we were," said Roland Rollins, a New Dominion supervisor, "but we sure didn't want to be the cause of it, so that's why we thought, well we'll just take the positive approach and find out."

With the help of OGS, the company installed two seismic stations on its property in south Oklahoma City, but the wells are 10 to 15 miles from the general location of all the earthquakes, and the monitors are not picking up any unusual seismicity, so Holland has pretty much ruled them out.

But what about other injections wells? Holland said he's looked and the ones closest to the seismic activity are all low-volume and low-pressure. What's more, he said, the earthquakes, unlike those in Dallas a year ago, are spread out.

"If it was triggered seismicity, you'd expect the earthquakes all to be located in a fairly small spatial area," Holland said.

And still, you don't have to be a skeptic to wonder how a 10,000 percent increase in seismic activity could not be triggered.

So we asked Holland if he would have a problem saying the earthquakes were tied to oil and gas activity, if the data pointed to that.

"No," Holland emphasized, "that would be very important...[but] I just can't make the connection, there just doesn't seem to be a link, and it's the easy answer. Everyone wants to pin it on the oil activities, but it just doesn't seem to be there yet."

Whether the earthquakes are induced or somehow the work of nature, they are taking a toll, as many people, like Jenifer and Chris, are now paying for earthquake insurance.

"For the most part, it's become kind of just part of life, but you would kind of like to know what the answer is," Reynolds said.

Holland said he hasn't completely ruled out the possibility the quakes are induced (man-caused), saying he still has much more analysis to do. He said he hopes to publish the results of his research in about a year.