Bechtel explained to Sunday Night that if your home happens to be built over limestone, beneath it the ground will be “like Swiss cheese” and riddled with caves. Groundwater dissolves the limestone until, in the right conditions, all it takes is heavy rain or a faulty sewer to trigger a dramatic and dangerous sinkhole.
“A sinkhole is basically a hole underneath the ground that is slowly eating its way up. The roof gets higher and higher until the weight of someone walking over the top or a truck driving over collapses the roof.
"That vertical tunnel has probably been eating its way up for days, if not months or years.”
He also believes human activity is causing more sinkholes than ever before. In the right conditions something as simple as urban drainage, that concentrates water runoff in one place rather than dispersing it, can cause a sinkhole.
“Sinkholes happen naturally but very, very rarely. Without humans around, one sinkhole may occur in a lifetime," Bechtel said.
"It’s scientifically fascinating, but from a human standpoint it is very much a tragedy. I think people have a right to be very nervous. There are going to be a lot more catastrophic sinkholes.”
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Apparently Mt Gambier is likely to develop a sinkhole. Although we had one here a few years ago in Bellevue Hill:
Sinkhole Swallows Sydney Street
