January 03, 2013
The Sinkholes of Berezniki
Once upon a time, in an old mining city in Russia's Ural Mountains, potash was extracted from salt lying about a fifth of a mile beneath the surface.
Wrote Andrew E. Kramer in the New York Times, "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" after a freshwater spring began flowing into the mine in October 2006."
"So grave is the danger that the entire city is under 24-hour video surveillance. On a screen in the command center [top] 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."
More excerpts from the Times article follow.
Sinkholes are common hazards in mining regions, plaguing areas where miners have burrowed into layers of soluble minerals and accidental floods have followed. But in Berezniki, as often happens in Russia, the problem has been magnified by past practices in which safety was not always the foremost concern.
In the West, mines are usually located far from populous areas, to reduce the risks of sinkholes to homes and other buildings. But Berezniki, a city of 154,000 that began as a labor camp, was built directly over the mine — a legacy of the Soviet policy of placing camps within marching distance of work areas.
And so Berezniki is afflicted by sinkholes, yawning chasms hundreds of feet deep that can open at a moment’s notice.
While scientists have so far successfully predicted each sinkhole, the chasms can open with astonishing speed. On December 4, 2011, as Olga V. 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.
The local government adopted the policy in effect today, of careful observation and early warning: geologists, surveyors and emergency personnel use a panoply of high-technology monitors. These include the video surveillance system, seismic sensors, regular surveys and satellite monitoring of the changes in altitude of roofs, sidewalks and streets.
"We will fight the holes with science," the mayor, Sergei P. Dyakov, said in an interview. The city will not need to relocate, he said, because engineers believe that no new holes will open. Much of the mine was filled before the flood, he said, and the sinkholes occurred in an anomalous area [below] that had not been filled in.
But federal officials and company executives are debating whether to relocate the entire city to the opposite bank of the Kama River, where the bedrock is solid.
The largest hole opened in July 2007. Experts at Uralkali say it may be the largest manmade sinkhole in the world. Residents, who have given all the holes nicknames, call it "The Grandfather."
The municipal authorities were compelled to evacuate about 2,000 people from nearby apartment blocks [below],
at great expense. The Grandfather is now 340 yards wide and 430 yards long, and it plunges right to the salt strata underneath the city — 780 feet, or the equivalent of 50 stories, straight down. It partly destroyed a warehouse near its edge.
The next hole appeared on a snowy night in November 2010, underneath a railroad siding. As dirt funneled in, the railroad tracks remained suspended over the abyss for a time. Then a boxcar tumbled in. That hole became known as "the Young One." It sucked in a row of storage sheds and a parked Moskvich passenger car.
"We are afraid but don’t know what to do," Tatyana Shishkina, a city resident, said in an interview in her living room [below],
where the ceiling is cracked and appears ready to cave in. About 60 apartment blocks, including this one, are so badly damaged from subsidence that they will have to be abandoned, even though no holes have appeared nearby.
The authorities are left trying to soothe nerves.
"Why worry about this all the time?" Natalya N. Verbitskaya, the mayor’s press aide, said in an interview. "You will spoil your mood."
Census data, though, shows that about 12,000 people voted with their feet, leaving the town between 2005 and 2010. Those who remain in Berezniki are on the watch for holes. And its name has shown up on Web sites that are a blow to civic pride, like "The World’s Largest Sinkholes: Doorways to Hell."
In one district of abandoned homes, the walls yellowed with mold and the windows shattered, old fliers are still pasted to corkboards beside the doors. "Sober Movers," says one. "We move anything from a piano to a safe, assemble and disassemble furniture. Our movers are always sober."
It is always a bit poignant and stirring for me to read stories like this one about my ancestral home (both my parents were born in the U.S.S.R. in what is now Russia).
Perhaps there is something to the old saw about blood.
January 3, 2013 at 04:01 AM | Permalink
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