Humans are hopeless when it comes to earthquakes, right? Not so, according to Christian Klose, a geohazard researcher (who knew there's such a thing?) at Columbia's Lamont-Doherty Earth Observatory. He is arguing that human activities can cause earthquakes:
"In the past, people never thought that human activity could have such a big impact, but it can" [...] It turns out, actually, that the human production of earthquakes is hardly supervillain-worthy. It's downright commonplace: Klose estimates that 25 percent of Britain's recorded seismic events were caused by people.
Most of these human-caused quakes are tiny, registering less than four on geologist's seismic scales. These window-rattlers don't occur along natural faults, and wouldn't have happened without human activity -- like mining tons of coal or potash. They occur when a mine's roof collapses, for example, as in the Crandall Canyon collapse in Utah that killed a half-dozen miners last year.
But some human actions can trigger much larger quakes along natural fault lines. That's because humans, with the aid of our massive machines, can sling enough mass around to shift the pattern of stresses in the Earth's crust. Faults that might not have caused an earthquake for a million years can suddenly be pushed to failure, as Klose argues occurred during Australia's only fatal earthquake in 1989.
http://blog.wired.com/wiredscience/2008/06/top-5-ways-that.html