Distant powerful temblors triggered ominous activity at wastewater injection sites
Courtesy of Science/AAAS
Giant, distant earthquakes may help scientists identify places where humans are liable to set off smaller tremors when they inject fluid deep into geologic deposits.
Scientists have known for decades that injecting huge volumes of liquid underground — such as waste from hydraulic fracturing, or fracking — can set off quakes. But in most cases it doesn’t, and scientists can’t predict when or where such human-induced earthquakes will happen.
In the July 12 Science, seismologists report that massive earthquakes unleash seismic waves that can trigger tremors near wastewater disposal wells half a world away. The tiny quakes may be a warning sign that a fault is close to rupture.
“When we do see remote triggering, it seems to foreshadow larger induced earthquakes,” says coauthor Nicholas van der Elst of Columbia University’s Lamont-Doherty Earth Observatory in Palisades, N.Y. “It shows the faults are reaching a tipping point.”