Russian City May Collapse Into Potash Mine

NYT, via nc links:

And so Berezniki is afflicted by sinkholes, yawning chasms hundreds of feet deep that can open at a moment’s notice. So grave is the danger that the entire city is under 24-hour video surveillance. On a screen in the command center late last year, one such hole appeared as a small dark spot in a snowy field in the predawn hours, immediately threatening to suck in a building, a road and a gas station.

“I looked and said, ‘Wow, a hole is forming,’ ” recalled Olga V. Chekhova, an emergency services worker who monitors the video. This was a small one by the standards of Berezniki, which has had three in the past four years. In fact, it has since been called “The Tiny One.”

While scientists have so far successfully predicted each sinkhole, the chasms can open with astonishing speed. On Dec. 4, as Ms. Chekhova watched the dark spot on her screen expand, witnesses began calling an emergency number for reporting sinkholes. They had heard a loud swooshing noise.

As the police cordoned off the area that day, dirt and snow tumbled in. Before noon, the sinkhole was 25 yards across.

Berezniki’s problems have been traced to October 2006, when a freshwater spring began flowing into the mine, where potash fertilizer is extracted from salt lying 720 to 1,500 feet below the surface. The problem is that the walls and pillars of salt that miners had left to support the ceilings of huge underground caverns began to dissolve.

Wow,  I'll take U.S. regulation any day over this clusterfuck.