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Coal Mining causes Newcastle Earthquake


The most damaging earthquake in Australia's history was caused by humans, new research says. The magnitude 5.6 quake that struck Newcastle, in New South Wales, on December 28, 1989, killed 13 people, injured 160, and caused 3.5 billion U.S. dollars worth of damage. 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 of Columbia University's Lamont-Doherty Earth Observatory in Palisades, New York.

The quake wasn't enormous, but Australia isn't generally considered to be seismically active and the city's buildings weren't designed to withstand a temblor of that magnitude, Klose said. All told, he added, the monetary damage done by the earthquake exceeded the total value of the coal extracted in the area. Klose presented his findings at a meeting of the American Geophysical Union in San Francisco, California last month.

Heavy Burden
"The removal of millions of tons of coal from the area caused much of the stress that triggered the Newcastle quake," Klose said.

He said his modelling and simulations showed mining "was likely to trigger the . . . Newcastle earthquake at a depth of 11.5 kilometres after 188 years of black coal mining" - the same depth that Geoscience Australia gives for the epicentre.

But even more significant was groundwater pumping needed to keep the mines from flooding. "For each ton of coal produced, 4.3 times more water was extracted," Klose said.

Dr Klose said "dewatering" mines removed millions of tonnes of groundwater from Newcastle over the years, adding to "destabilisation in the Newcastle fault."

Other mining operations, he added, sometimes require as much as 150 tons of water to be removed for each ton of coal produced. "So this is on the low end," he said.


Sydney Morning Herald story


Christian D Klose
Doctor of Sciences
Research on Natural Hazards and Sustainable Development
Lamont-Doherty Earth Observatory
Centre for Hazards and Risk Research
Phone ++1-646-321-7538