Fracking is not the cause of quakes. The real problem is wastewater. 

Fracking is not the cause of quakes. The real problem is wastewater.

Okla. looks at fracking and a rise in earthquakes

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A dramatic increase in earthquakes in Oklahoma has many people asking about the role of deep wells where oil and gas firms inject wastewater from extraction techniques such as hydraulic fracturing.

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An increase in Oklahoma earthquakes has many people asking about the role of oil and gas firms’ wastewater disposal wells.

 Jan. 26, 2015 Oklahoma Geological Survey seismologist Amberlee Darold wires a solar-power panel to a seismometer in Oklahoma City as part of efforts to determine whether a major increase in earthquakes is related to oil and gas exploration. Linda Davidson/The Washington Post

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Wastewater wells are the issue

Hydraulic fracturing, or fracking, extracts far more water from these underground oil-laden rocks than traditional drilling. Currently there is no way to treat, store and release the billions of gallons of wastewater at the surface. Instead, drillers pump the fluid back underground, below groundwater, into wells where it sometimes triggers earthquakes.
For instance, in Oklahoma, state records show that companies injected more than 1.1 billion barrels of wastewater into the ground in 2013, the most recent year for which data is available. The following year, Oklahoma had more magnitude-3 earthquakes than California did. The quakes clustered around wastewater injection wells.
Oklahoma’s current earthquake rate is now 600 times higher than its pre-fracking rate, which was based on the state’s natural seismicity, the state geological survey said.

[Okla. worries over swarm of earthquakes and connection to oil industry]

“We suspect the vast majority of these earthquakes are from produced wastewater,” said Austin Holland, head seismologist for the Oklahoma Geological Survey.
Fracking itself can also induce earthquakes, but the technique has never caused earthquakes greater than magnitude 4. For comparison, an Oklahoma injection well is thought to have triggered a magnitude-5.6 earthquake in 2011. Mining blasts and geothermal energy plants can also trigger earthquakes.

Quake road map

Until now, the USGS has usually excluded induced earthquakes from its earthquake hazard maps. The researchers who make the maps assume earthquake rates are more or less the same through time, and that’s not the case with man-made quakes.

Map: Earthquakes and drilling in Oklahoma View Graphic

“These earthquakes are different from natural earthquakes because they turn on and off over short periods of time, sometimes over a period of a year,” Petersen said.
So even as north central Oklahoma and Texas were suffering swarms of earthquakes, the 2014 hazard map showed little to no shaking risk for these states. The national map shows where earthquakes may strike in the next 50 years, how big they might be and how strong the shaking could get.

Central U.S. risk

But now there is no way for scientists to ignore the incredible rise in earthquakes in the central United States. With input from more than 150 scientists, the USGS decided to release a separate earthquake hazard map for man-made earthquakes. Researchers gauged a region’s shaking risk by first looking for changing earthquake rates. Then the scientists counted the previous year’s temblors to forecast the next year’s tally.
A one-year model is not useful for issuing building permits, but it is helpful for planning where to spend limited funds on bridge repairs and for other decisions, said Bill Ellsworth, a USGS seismologist who is studying injection-well earthquakes.
A simplified version of the man-made earthquake hazard map will be published by the end of the year and will be updated yearly thereafter, Ellsworth said. (The agency will continue to issue the long-term forecasts every six years.) Scientists are still fine-tuning models that predict the shaking strength from man-made earthquakes, which tend to be shallower than natural quakes.
Researchers involved in the mapping project called for expanded seismic networks and public access to well-injection records last week at the annual meeting of the Seismological Society of America. Only a few injection wells cause headaches, so this data may help determine whether small earthquakes at wells could lead to more-damaging ones.
“This monitoring would fundamentally change how often and how accurately we can update these maps,” said Andy Michael, a USGS geophysicist in Menlo Park, Calif,, who was involved in the project.