In the last year alone they have caused houses, apartment blocks, roads and even a sleeping man, to disappear into the ground without warning – and every year there are more destructive sinkholes than ever before. Mount Gambier is one of a very small handful of places in the world with the soft limestone bedrock that creates deep, circular, spectacular sinkholes like the ones found in Mexico and Florida.
Beneath the regional center of Mount Gambier is a myriad of caves. According to Aussie geologist and sinkhole buff, Ian Lewis, the only things keeping them from collapsing are the dry conditions and relatively stable water table.In addition to southern Australia’s Limestone Coast, the northern suburbs of Perth, parts of Canberra, Newcastle, the Nullarbor Plain and western NSW have have seen sinkholes appear in recent years.Australia’s largest sinkhole has a lake at its floor and it is a popular tourist attraction, but our diving expedition to the bottom of two at Ewen's Ponds and Piccaninnie Ponds, which no one has ever been to the bottom of, revealed the caves that could be the next sinkholes waiting to happen. Preventing Sinks holes by Redirecting or Blocking Water,Treating Underground Limestone, Construction Measures, Avoid Construction on Wetlands, Seawater Treatment Facilities, Recycling Grey Water Run-off.
Humans do contribute to sinkholes and probably have ever since the invention of irrigation. Anything that has the potential to divert water into weak points beneath the earth will accelerate the creation of the pits into which houses, cars and unfortunately people sometimes fall. The drying out of the ground by abstraction or the soaking from a burst pipe are the most direct examples of human-caused sinkholes.
Sources:
http://www.theaustralian.com.au/news/the-season-for-sinkholes/story-e6frg6n6-1226597176224
http://www.smh.com.au/environment/sinkhole-swallows-southeast-queensland-beach-20110626-1gm67.html
Excellent entry Rob, and that is an incredible picture. I've never heard of treating underground limestone, but that sounds like a great idea. Do you know to what extent it has been employed in Australia?
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ReplyDeleteI really enjoyed reading your blog and to your point about humans contributing to sinkhole formation, underground mining, water extraction, oil and gas extraction all contribute to the problem. That is probably why it happens more frequently than it probably should and there are already inherent causes which lead to this geological phenomenon: dissolution of rocks such as limestone, dolostone and marble, thawing of frozen ground, compaction of deposited sediment, earthquakes and underground drainage of magma...I would think we wouldn't need to make the problem more serious than it is, but certainly our actions contribute to a big extent to current sinkholes problems.
Great post Rob. I found it interesting in how there is caves and lakes at the bottom of these sinkholes. That is crazy to think about. The whole situation with irrigation and how pumping water from the ground reminded me about that picture of the San Joaquin Valley depression. Just from human interference, the ground in that area dropped 8 meters. It is amazing how that works.
ReplyDeleteRob, nice post,, that pic is sinkhole of all sinkholes....what happened to the disappearing man? I did not know sinkholes were somewhat associated with caves? I was also unaware Australia had such a sinkhole issue lately. have a pretty little sinkhole and underground cave on my blog. Check it out.
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