This reminds me of Kalgoorlie (gold minning town in WA). I was there in the early nineties and we had a huge random storm which did a lot of damage to the buildings in town. One report covered a car that had dissapeared into a big hole that opened up in the owners garage due to the deluge . The locals reckon there are more tunnels and abandoned mines under the place than you can poke a stick at.
The Mirny Diamond Mine holds the title of the largest open diamond mine in the world. Its 525m deep and has a diameter of 1200m, and there is a no-fly zone above the hole as a few helicopters got sucked in.
???
Marki, I lived in Kal in '83, was only 8yo at the time, but remember a day when one of the larger mines was doing a large blast.
They warned the whole town, every miner was ordered not to be in their mines.
I remember sitting up at the reservoir with my parents(and almost everyone else in town), an air-raid like siren sounded all thru town, then the blast went off.... as far as the eye could see there were little mushroom clouds puffing up from other mines that had cave-ins!
My child memory is of hundreds of little puffs, tho in reality there was probably only a couple of dozen.
Actually, it reminds me of the Beatles song "A day in the life." -- Sgt Peppers Lonely Hearts Club Band.
"... I read the news today oh boy,
4000 holes in Blackburn Lancashire.
And though the holes were rather small,
they had to count them all,
now they know how many holes it takes to fill the Albert Hall ..."
Back in Feb this year I was in Arizona. My son, Andrew, and I visited a number of landmarks in that state. The Grand Canyon helicopter flight was unreal. That hole took a long time to excavate. But the one that really gave me goose bumps was the Barringer Meteorite Crater. 750 feet deep and 4000 feet diameter in seconds. 176 million tons of rock was shifted.
From memory the meteor was about 150 feet diam and weighed around, I quote:
Scientists now believe that the crater was created approximately 50,000 years ago. The meteorite which made it was composed almost entirely of nickel-iron, suggesting that it may have originated in the interior of a small planet. It was 150 feet across, weighed roughly 300,000 tons, and was traveling at a speed of 28,600 miles per hour (12 kilometers per second) according to the most recent research. The explosion created by its impact was equal to 2.5 megatons of TNT, or about 150 times the force of the atomic bomb that destroyed Hiroshima.
Its amazing to see it in real life. I've been there. I say go see it yourself if you ever can do.
Amazing holes in Earth
. The locals reckon there are more tunnels and abandoned mines under the place than you can poke a stick at. 
That hole took a long time to excavate. 
But the one that really gave me goose bumps was the Barringer Meteorite Crater. 750 feet deep and 4000 feet diameter in seconds.
