"U.S. 285 south subject to sinkhole 1,000 feet ahead," reads a bright yellow sign along the stretch of highway heading through Carlsbad, N.M.

Normally a motorist driving through the area might not find a sign like that unusual. The city is, after all, home to Carlsbad Caverns National Park, a network of some of the largest natural caverns in North America. But on this occasion, the sign's sharp colors make the message clear: what's happening in Carlsbad is not natural.

In fact, the massive sinkhole currently running through the center of town was created by the oil industry. As MSNBC reports, it was formed over three decades as oil field service companies pumped fresh water into a salt layer more than 400 feet below the surface and extracted several million barrels of brine to help with drilling.

If it collapses, the unnatural cavern is likely to take with it a church, a highway, several businesses and a trailer park. Massive fissures currently cleave through town, and one business owner has said that structural cracks have even formed in his store.

"It would be like a bomb going off in the middle of town," said Jim Griswold, a hydrologist with the New Mexico Oil Conservation Division. The problem is so severe that the Eddy County Commission declared a state of emergency last Thursday, and they hope that state and federal funds will arrive in time to fill the cavern before it collapses.

Alarms placed to monitor the sinkhole should give authorities at least a few hours' warning to evacuate Carlsbad's residents in the event of an imminent cave-in, but the costs of the sinkhole might already be inevitable. Damages to local crops could exceed $100 million.

In regular industry fashion, the oil field service company that owns the site where the cavern is located, I&W Trucking, contends the state is overreacting. But if anyone knows how to judge the dangers of a giant hole in the ground, it's the 26,000 residents of Carlsbad, N.M.

"It's a nightmare," said Ellie Fletcher, a local resident. "I would like to forget about it, but I can't forget about it because it's right there."

Meanwhile, I&W Trucking has abandoned its brine operation and moved down the road.

Bryan Nelson ( @@brynelson ) writes about everything from environmental problems here on Earth to big questions in space.

Oil industry sinkhole threatens to swallow city
Parts of New Mexico town near Carlsbad Caverns National Park could collapse because of irresponsible extraction practices by the oil industry.