Shale Shocked: ‘Remarkable Increase’ In U.S. Earthquakes ‘Almost Certainly Manmade,’ USGS Scientists Report
A U.S. Geological Survey (USGS) team has found that a sharp jump in earthquakes in America’s heartland appears to be linked to oil and natural gas drilling operations.
As hydraulic fracturing has exploded onto the scene, it has increasingly been connected to earthquakes. Some quakes may be caused by the original fracking — that is, by injecting a fluid mixture into the earth to release natural gas (or oil). More appear to be caused by reinjecting the resulting brine deep underground.
Last August, a USGS report examined a cluster of earthquakes in Oklahoma and reported:
Our analysis showed that shortly after hydraulic fracturing began small earthquakes started occurring, and more than 50 were identified, of which 43 were large enough to be located. Most of these earthquakes occurred within a 24 hour period after hydraulic fracturing operations had ceased.
In November, a British shale gas developer found it was “highly probable” its fracturing operations caused minor quakes.
Then last month, Ohio oil and gas regulators said “A dozen earthquakes in northeastern Ohio were almost certainly induced by injection of gas-drilling wastewater into the earth.”
Now, in a paper to be deliver at the annual meeting of the Seismological Society of America, the USGS notes that “a remarkable increase in the rate of [magnitude 3.0] and greater earthquakes is currently in progress” in the U.S. midcontinent. The abstract is online.EnergyWire reports (subs. req’d) some of the findings:
The study found that the frequency of earthquakes started rising in 2001 across a broad swath of the country between Alabama and Montana. In 2009, there were 50 earthquakes greater than magnitude-3.0, the abstract states, then 87 quakes in 2010. The 134 earthquakes in the zone last year is a sixfold increase over 20th century levels.
The surge in the last few years corresponds to a nationwide surge in shale drilling, which requires disposal of millions of gallons of wastewater for each well. According to the federal Energy Information Administration, shale gas production grew, on average, nearly 50 percent a year from 2006 to 2010.
I foresee a study in the near future, paid for by the oil industry, that concludes the increase in little earthquakes is actually serving to reduce the frequencies and magnitudes of large ones.