The Bayou Corne Sinkhole

Underneath the wetlands of Louisiana and southeastern Texas are vast deposits of salt, extending a mile under the earth. Geologists call these deposits "domes." Salt mining has been going on in the area for a long time now. These days it is done by "injection mining," which means injecting high-pressure water into the earth, collecting the salty water that emerges and then extracting the salt from it. Once large caverns have been hollowed out within the salt, they make good places to store things like oil and natural gas; most of our strategic petroleum reserve is housed in salt dome caverns far under the earth.

But as geologist Robert Traylor told Mother Jones, "In the oil business, a million things can go wrong, and they usually go wrong." At Bayou Corne in Lousiana, something very bad went wrong in August 2012. A giant salt cavern far under the earthcollapsed, creating a rapidly-expanding sinkhole now 750 feet deep and covering 24 acres. The 350-person town has been evacuated, since nobody really knows what is happening under the surface or how bad things might get. Texas Brine, the company drilled out this particular cavern, certainly does not know, and the state of Louisiana has filled a lawsuit against them alleging that they did not do the proper geological studies of the dome:

Texas Brine's Oxy3 cavern, one of 53 in the Napoleonville Dome and one of six operated by the company, is more than a mile below the surface. At that depth, 3-D seismic mapping is both time-consuming and expensive, and as a consequence, injection-mining companies often have only a foggy—and outdated—idea of what their mines really look like. "Everybody wants to do it within a certain budget and a certain time frame," explains Jim La­Moreaux, a hydrologist who organizes an annual conference on salt-cavern-caused sinkholes. In some cases, he says, it's possible that companies cut corners and fail to commission the proper studies.

Texas Brine's first and last mapping project was in 1982, and by the company's own admission, it understated Oxy3's proximity to the edge of the salt dome and the possibility of a breach. When another company surveyed the dome a few years ago, it found that Texas Brine's cavern was less than 100 feet from the outer sheath of oil and gas, far closer than is permitted in other states. While Louisiana had restrictions on gas storage caverns, it had nothing on the books for active brine wells—only what regulators called a "rule of thumb" that wells be set back 200 feet. . . .

You can get an idea of how fast the sinkhole is growing from this video, which shows it swallowing a stand of cypress trees. The boom is there to contain the large amounts of crude oil that bubble to the surface from time to time.

In Oklahoma, fracking has caused earthquakes. In Louisiana, injection mining has already led to the permanent abandonment of a couple of small towns, and it seems to be claiming another. There are always consequences to things like messing around deep under the earth.