January 07, 2007

Coal mining may have caused quake. On Thursday 28 December 1989, at 10.27am, Newcastle in New South Wales, Australia had a 5.6 earthquake. This new study thinks it may have been the coal mining activities (taking out millions of tons of coal and pumping out groundwater) that was the trigger, not natural intra-plate tension.

You may be curious as to why this earthquake has so much focus on it. Mainly it's because Australia doesn't have all that many quakes - and very few large ones, being on their own tectonic plate. You can clearly see very earthquake active areas here on this world density earthquake map as well as this map showing earthquakes, volcanoes and plate tectonics. Earthquake DB and the World-Wide Earthquake Locator are also helpful for seeing the frequency of earthquakes in certain areas. Places such as California, Japan and several other countries on the Pacific "Ring of Fire" are well-known as having frequent earthquakes, and although you don't often hear about them Canada seems pretty concerned too. (To assist you with checking out these sites it should be noted that there are 4 scales used to measure quakes depending on the area - the Richter, Mercalli, Japanese Shindo and European Macroseismic)

posted by gomichild 17 years ago
  • Great post, gomi. I was in Sydney when this one went down, and even at that distance the (brick)house shook like a leaf for fifteen seconds or so. I will never forget the look on my ex-wife's face as she clambered out of the outside toilet completely bewildered. "Ma putain, c'était quoi ça? Hein?"
  • Any explosion or event of significant size can create a seismic signal. The explosion on the Russian sub Kursk and the falling of the World Trade Centers are just two examples. A seismic signal (shake) is not the same as an naturally occuring earthquake, though both may rattle the ground you are standing upon. "Intentionally detonated mine or quarry explosions and planned roof collapses produce seismic signals that are broadly similar to the seismic signals produced by earthquakes, and the process of monitoring natural seismicity has therefore involved identifying these routinely occurring mining seismic events and ensuring that they are not misidentified as natural earthquakes."
  • Related discussion: Forensic Seimology
  • Interesting links mercurious but I think there is no doubt that this earthquake was an actual earthquake. The big question is - was it a natural forming quake - or did the process of large mining - a massive disturbance over a period of time cause it?
  • Earthquakes occur when there is a break in materials in the brittle crustal layers (but generally at the brittle-ductile transition, which is a big topic in itself). If this coal mining operation caused a situation of differential stress that was high enough, it could have caused the earthquake. It's a matter of scale and initial stability. From what the article says, the subsurface had become a dense network of tunnels, and a lot of water was removed. When the subsurface materials are removed, subsidence occurs, and if there is enough subsidence fast enough, an earthquake can occur.
  • All of the article on this subject say: That quake was triggered by changes in tectonic forces caused by 200 years of underground coal mining, according to a study by Christian D. Klose. You can believe what you like, but it is important to note that this is suggested by one man's study. Although he is beginning to present his ideas at conferences, this has apparently not yet been published in a peer-reviewed publication. Jumping the gun by simply accepting an idea (no matter how attractive) without scrutiny is, IMHO, premature.
  • Well I don't think anyone is in this thread is professing a total belief in this, but it has value as a question to be looked at.
  • Klose, C.D. (2006). Nexus of natural energy resources, human-triggered earthquake risks and sustainable development in Central Asian Republics, In: Management of Urban Earthquake Risk in Central Asian and Caucasian Countries, NATO ASI Series (accepted). Klose, C.D. (2006). Geomechanical Modeling of the Nucleation Process of Australia's most costly Earthquake, Earth and Planetary Science Letters (accepted). Klose, C.D. (2006). Health risk analysis of volcanic SO2 hazard on Vulcano Island (Italy), Natural Hazards (accepted). OK, so "not yet been published in a peer-reviewed publication", but surely "accepted" means "peer-reviewed"?
  • Yeah, but everyone knows that the NATO ASI Series is put out by one of those vanity presses.
  • Must say I dislike the initial sensation of me being at fault, so to speak, during a quake. Then realize, Oh. Earthquake. Which realization never saves me from feeling like an idiot for not realizing it sooner. In a just world I'm convinced I would immediately intuit the fact a quake was happening, but so far my ESP seems defective.
  • Precipitated.
  • I seem to remember first hearing about this effect in Jared Diamond's "Collapse", but I could be wrong.
  • 5.6? Wimpy. (Says this native San Franciscan.)
  • see if you can work out where the poster lives
  • Just had a 4.3 here.
  • Today we are waiting for tsunami to hit.
  • Yikes. News says the warning is downgraded to an "advisory" now.