7 million Americans at risk of man-made earthquakes, USGS says
By Joel Achenbach March 28 at 12:59 PM
U.S. Geological Survey map shows the potential for Americans to experience damage from natural or human-induced earthquakes in 2016. Changes range from less than 1 percent to 12 percent. (Courtesy of USGS)
Earthquakes are a natural hazard -- except when they're man-made. The oil and gas industry has aggressively adopted the technique known as hydraulic fracturing, or fracking, to shatter subsurface shale rock and liberate the oil and gas lurking there. But the process results in tremendous amounts of chemical-laden wastewater. Horizontal drilling for oil can also produce massive amount of natural, unwanted salt water that cannot be efficiently recycled. The industry disposes of all this wastewater by pumping it into deep wells.
And the Earth moves.
[Fracking is not the cause of quakes. The real problem is fracking wastewater.]
On Monday, the U.S. Geological Survey published for the first time an earthquake hazard map covering both natural and "induced" quakes. The map and an accompanying report indicate that parts of the central United States now face a ground-shaking hazard equal to the famously unstable terrain of California.
Some 7 million people live in places vulnerable to these induced tremors, the USGS concluded. The list of places at highest risk of man-made earthquakes includes Oklahoma, Kansas, Texas, Arkansas, Colorado, New Mexico, Ohio and Alabama. Most of these earthquakes are relatively small, in the range of magnitude 3, but some have been more powerful, including a magnitude 5.6 earthquake in 2011 in Oklahoma that was linked to wastewater injection. Scientists said Monday they do not know if there is an upper limit on the magnitude of induced earthquakes and that this is an area of active research.
USGS map displaying 21 areas impacted by induced earthquakes as well as the location of the fluid injection wells that have and have not been associated with earthquakes. (Courtesy of USGS)
It's not immediately clear whether this new research will change industry practices, or even whether it will surprise anyone in the areas of newly estimated risk. In Oklahoma, for example, the natural rate of earthquakes is only one or two a year, but there have been hundreds since fracking and horizontal drilling, with the associated wastewater injection, became commonplace in the last decade.
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"By including human-induced events, our assessment of earthquake hazards has significantly increased in parts of the U.S.,” Mark Peterson, chief of the USGS National Seismic Hazard Mapping Project, said in a release.
The report, based on recent seismic activity, is just a one-year hazard assessment. In effect, the scientists have said that what has happened in the recent past with induced earthquakes will likely happen in the near future. Past USGS hazard maps didn't include man-made events.
“Having it quantified authoritatively will be helpful in establishing just how much danger there is," Michael Blanpied, associate coordinator of the USGS Earthquake Hazards Program, told The Post.
USGS map displaying 21 areas where scientists have observed rapid changes in seismicity that have been associated with wastewater injection. The map also shows earthquakes - both natural and induced - recorded from 1980 to 2015 in the central and eastern U.S. with a magnitude greater than or equal to 2.5. (Courtesy of USGS)
The earthquake hazard is hard to estimate in any given moment and in any given place, in part because natural earthquakes are inherently unpredictable. The oil and gas industry is unpredictable, too. With oil prices low, companies have cut back on drilling recently.
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The cut-back in production may explain why, in recent months, there have been fewer earthquakes in southern Kansas, said Rex Buchanan, director of the Kansas Geological Survey.
With a few exceptions, locations in the nation's central and eastern regions are not generally thought of as seismically unstable. But, Blanpied said, “Pretty much everywhere has faults. The nation was built over a billion years, and lots and lots of faults are left over from the construction process.”
The fluids injected into the deep wells don't lubricate the faults so much as put additional pressure on them, driving their walls apart, he noted.
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A fault running between Dallas and the adjacent city of Irving caused a magnitude 3.6 earthquake in January 2015. That was attributed to natural causes, though an injection well was only about six miles away, said Heather R. DeShon, a seismologist at Southern Methodist University. But the USGS identifies the huge Dallas metropolitan area as one of the main places vulnerable to a significant earthquake because of human factors.
“The new map serves as a reminder to the local populations living with the recent earthquakes that it is best to be prepared to feel ground shaking," said DeShon, who was not involved in the new study.
The Dallas Morning News reported that an unreleased study by the Federal Emergency Management Agency estimated that a worst-case, 5.6 magnitude earthquake hitting Dallas could damage 80,000 buildings, cause levees to collapse and lead to $9.5 billion in economic losses.