Human-induced earthquakes are happening in places like Colorado, New Mexico, Wyoming and Utah. Though some fracking-related quakes have now been documented (including a 4.4-magnitude quake in Alberta this January), the majority of non-tectonic quakes are caused by the disposal of industry wastewater through underground injection. Even relatively minor quakes can be dangerous when they happen in unprepared places, such as the Interior West, where hazard maps and building codes may not have been created with tremors in mind. Complicating the issue, it’s hard for officials and researchers to predict where drilling or mining might create problems.
“There are more than 100,000 of these injection wells in the U.S., and only a few of them have caused earthquakes,” Anne Sheehan, a geophysicist at the University of Colorado, says. “If we learn more about what’s causing these earthquakes, we have more of a chance of reducing the odds of them happening.” In a paper published in Science magazine in February, Sheehan and other researchers argue for better study of earthquakes that might be human-induced.
Within days of a suspicious earthquake near Greeley, Colorado, last June, Sheehan and other researchers installed several seismometers nearby. They were able to pinpoint the injection well that caused the quake. It was injecting at a high rate, over 300,000 barrels per month — and was still causing tremors. The Colorado Oil and Gas Conservation Commission temporarily shut down the well and lowered its rate of injection. “Now the earthquakes have really tapered off,” Sheehan says. “Last summer, there were hundreds of small earthquakes there, and now there are very few.”
This article appeared in the print edition of the magazine with the headline Quake-makers.
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