Gas well fracking causing TX earthquakes?

Recently, a number of minor earthquakes have been reported in Texas’ natural-gas laden Barnett Shale, centered in the area around Cleburne, south-southwest of Fort Worth. Now, with four earthquakes, all minor and below magnitude 3.0, hitting in less than a month, some people wonder if well fracturing isn’t the culprit.

Such work, known as fracking, involves shooting water supersaturated with a propriety type of sand, into a wellhead to widen it and to create cracks in the surrounding rock to get gas or oil to flow to the wellhead.

Chesapeake Energy, the main driller in the area, says it wants to get at the bottom of the issue, while, in the same breath, denies it’s the cause:

“Drilling has occurred for more than a hundred years,” Julie Wilson said in an e-mail. “Tens of thousands of wells have been drilled with no nearby earthquakes at all; hundreds of earthquakes have occurred with no drilling nearby.”

Per John Breyer, a petroleum geologist and professor at Texas Christian University, I agree; I doubt fracking is the cause.

But, how can you know for sure without checking, and, how can you check completely enough to “get at the bottom of the issue” if you’re already ruling yourself out as the cause in advance?

Beyond that, such a thorough check might also have other benefits.