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.
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The removal of millions of tons of coal from the area caused much of the stress that triggered the Newcastle quake, Klose said. But even more significant was groundwater pumping needed to keep the mines from flooding.