Something is shaking under Guy, Ark., and no one is sure what's causing the problem.

CNN is reporting that the small town north of Little Rock has had almost as many earthquakes since late September as it has residents. For the record, Guy has 549 residents and since Sept. 20, the town has had 487 measurable earthquakes. Arkansas is no stranger to seismic activity. CNN quoted Scott Ausbrooks, geohazards supervisor for the Arkansas Geological Survey, saying that last year the state had 39 measurable quakes.

Arkansas sits on top of several geological faults. One of these faults is the New Madrid fault, which is credited with causing a 7.0-magnitude quake back in 1811. The New Madrid fault is not that close to Guy, but another busy seismic area, known as the Enola Swarm is closer — 15 miles south of Guy. The Enola Swarm is known for causing up to 40,000 "microquakes" over the last 30 years. But most of these have gone unnoticed, which seems inconsistent with what is happening now.

So this is leading many in Guy to ask: what's shaking? The CNN report states that the town will have a meeting this week to discuss possible causes, including if this could be man-made. There is a lot of oil and natural gas production around Guy, but Ausbrooks seems to think that the nearby drilling could only be indirectly responsible for the quakes. "We see no relation to the drilling in the area, but we haven't ruled out a connection to the salt-water disposal wells," he said.

So what the heck are saltwater disposal wells? Essentially, these are wells that go as deep as 12,000 feet down and contain drilling wastewater from oil and gas production. There are reportedly several of these wells within several hundred square miles of Guy. 

Now, I don't want to go all James Inhofe on this, but I was a skeptical that man-made activity could cause earthquakes. But then I did some research and found that drilling of disposal wells near Derby, Colo., caused several quakes in the 1960s. So, it appears this theory is possible. In fact, there are other investigations about this same situation happening in Trinidad, Colo., about 10 years ago and then in north Texas where disposal wells were drilled near fault lines.

Now it seems as though Guy, Ark., has some investigating of its own to do. 

Is oil and gas production causing earthquakes in Arkansas?
Guy, Ark., has been hit with hundreds of earthquakes in the last few months, leaving many trying to figure out what is causing all the shaking.