Geohazards Supervisor Scott Ausbrooks said Tuesday that the Arkansas Geological Survey is continuing its work to analyze incoming natural gas injection well data.

Geologists have begun to study rates of injections and the timing of seismic activity in connection with at least two injection wells near Guy and Greenbrier.

Ausbrooks said that he cannot "discount the fact that (injection wells) have been found in other cases in other parts of the country to have triggered earthquakes."

Not every injection well produces seismicity, according to Ausbrooks.

"We know that this activity has caused earthquakes. This has been documented and was proven in the Rocky Mountain Arsenal in the 60s," Ausbrooks said. 

Ausbrooks referenced a former United States chemical weapons manufacturing center in Colorado, and the site of a deep fluid injection well.

"We can’t say that because there’s an injection well, there are earthquakes. There are thousands of wells across the country. What we’re looking at here, we’re looking at because the earthquakes occurred after the injections started," Ausbrooks said.

According to Ausbrooks, epicenters and injection well proximities also support a possible correlation between the two.

In January, a six-month moratorium was established on the construction of new injection wells in the area by the Arkansas Oil and Gas Commission.

The moratorium is intended to allow time for the AGS to study the possible relationship between the wells and area earthquakes.

"We’re going to work to figure out if this is true. We’ll look at the rate of injections and pressures to see if there’s a correlation with the amount of injection and earthquakes," Ausbrooks said.

Geologists ruled out fracking and excavation activities in 2010 as a potential influence, but injection wells, which have a much greater depth, were not.

The Greenbrier and Guy areas have experienced 31 earthquakes since Sunday’s record breaking 4.7 event.

Tuesday’s quakes numbered 10, with the last register being recorded at 10:29 a.m.

That event registered a 2.4-magnitude on the Richter scale, with its epicenter at three miles south of Guy.

Two quakes registered at 3.3 at 9:58 a.m. and 10:03 a.m. 

One event’s epicenter was found one mile north of Greenbrier, and the second, one mile north-northeast of Greenbrier.

A magnitude 3.2 was recorded at 4:06 a.m., with an epicenter four miles south of Guy.

Helicorder equipment at Woolly Hollow State Park recorded a 3.4-magnitude at 2:46 a.m. Monday. That event’s epicenter was three miles south of Guy.

(Staff writer Courtney Spradlin can be reached by e-mail at courtney.spradlin@thecabin.net or by phone at 505-1236. To comment on this and other stories in the Log Cabin, log on to www.thecabin.net. Send us your news at www.thecabin.net/submit)