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.
Mark