Latest Issue of Science News

4/18 Cover

News

Huge quakes may foretell smaller, human-caused ones

Distant powerful temblors triggered ominous activity at wastewater injection sites

By
10:59am, July 12, 2013

Over  the last few years, the number of earthquakes in the central and eastern United  States has increased along with the rise in wastewater disposal wells  associated with fracking. The map shows all of the magnitude 3 or greater  earthquakes that occurred in the United States in 2009-2012. Places with the  highest natural earthquake hazards are shown in red and orange while areas with  lower risk are shown in yellow and green.

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.”

This article is available only to subscribing members. Join SSP today or Log in.

More from Science News