From Green Right Now Reports
In a weird twist of global interconnectedness that only geologists could have predicted, a new study finds that major earthquakes in Chile and Japan appear to have triggered outbreaks of smaller quakes in U.S. regions where the oil and gas industry has drilled multiple waste injection wells.
Researchers found, for instance, that the 2010 Chile earthquake set off tremors near injection waste wells in central Oklahoma and southern Colorado.
Similarly, Japan’s massive 9.0 earthquake in March 2011 set off a ripple of smaller seismic activity near the West Texas town of Snyder, culminating in a 4.5 magnitude earthquake six months later. Snyder is the site of multiple injection waste wells, which oil and gas drillers use to dispose of chemically treated drilling fluids.These wells are the EPA-approved method for disposing of hazardous waste fluids.
The U.S. boom in shale oil and natural gas exploration, which employs hydrofracturing or fracking to crack into previously inaccessible oil and gas deposits, has rapidly increased the number of injection waste wells, which are being blamed for weakening the geology in heavily drilled areas.
“The fluids are driving the faults to their tipping point,” said Nicholas van der Elst, a postdoctoral researcher at Columba University’s Lamont-Doherty Earth Observatory and lead author of the article, which appears in Science this week. “The remote triggering by big earthquakes is an indication the area is critically stressed.”
The Oklahoma earthquakes began with a midsize quake less than a day after the 8.8 magnitude earthquake in Chile on Feb. 27, 2010. Less than 24 hours later, an area near Prague, OK, began experiencing a series of small quakes and later, a 5.7 magnitude earthquake on Nov. 6, 2011 that destroyed 14 homes.
The Oklahoma earthquake was considered the largest quake ever associated with injection wells.
This phenomenon of distant earthquakes triggering tremors elsewhere has been documented in the past, according to an article about the earthquake research issued by the Earth Institute at Columbia University. A major 2002 earthquake in Denali, Alaska, set off quakes in seismically sensitive Yellowstone and also triggered tremors around California’s San Andreas, San Jacinto and Calaveras faults, according to independent studies in 2004 and 2008.
Today’s new human-generated earthquakes don’t appear to imperil every area where the nation’s injection wells are clustered, but do threaten areas where the deepest wells have been drilled and filled, according to the study.
They also could worsen as drilling increases; serving as a warning, the researchers said.
“These passing seismic waves are like a stress test,” said study coauthor Heather Savage, a geophysicist at Lamont-Doherty. “If the number of small earthquakes increases, it could indicate that faults are becoming critically stressed and might soon host a larger earthquake.”
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