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USGS: Recent Earthquakes 'Almost Certainly Manmade'
Report implicates oil and natural gas drilling, aka fracking
A US Geological Survey research team has linked oil and natural gas drilling operations to a series of recent earthquakes from Alabama to the Northern Rockies.
According to the study led by USGS geophysicist William Ellsworth, the spike in earthquakes since 2001 near oil and gas extraction operations is “almost certainly man-made.” The research team cites underground injection of drilling wastewater as a possible cause.
“With gasoline prices at $4 a gallon, there’s pressure to rush ahead with drilling, but the USGS report is another piece of evidence that shows we have to proceed carefully,” said Dusty Horwitt, Senior Counsel and chief natural resources analyst at Environmental Working Group. “We can’t afford multi-million-dollar water pollution cleanups or earthquakes that could pose risks to homes and health.”
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Environmental Working Group analysis: USGS: Recent Earthquakes “Almost Certainly Manmade”; Report Implicates Oil and Natural Gas Drilling
The USGS authors said they do not know why oil and gas activity might cause an increase in earthquakes but a possible explanation is the increase in the number of wells drilled over the past decade and the increase in fluid used in the hydraulic fracturing of each well. The combination of factors is likely creating far larger amounts of wastewater that companies often inject into underground disposal wells. Scientists have linked these disposal wells to earthquakes since as early as the 1960s. The injections can induce seismicity by changing pressure and adding lubrication along faults.
The U.S. Energy Information Administration reports that between 1991 and 2000, oil and gas companies drilled 245,000 wells in the U.S. compared to 405,000 wells between 2001 and 2010 – a 65 percent increase.1 As an example of how much more fracking fluid is used, New York state’s review of oil and natural gas drilling regulations in 1988 assumed that companies would use between 20,000 and 80,000 gallons of fluid for hydraulic fracturing per well.2 The state’s 2011 review of regulations for natural gas drilling in shale formations assumed that companies would use 2.4 million to 7.8 million gallons of fluid per well – a 100-fold increase.3
According to Anthony Ingraffea, a professor of engineering at Cornell University who has conducted research on hydraulic fracturing, the increase in both the number of wells drilled and the amount of hydraulic fracturing fluid used per well has been driven by a shift of drilling into so-called unconventional formations such as shale in which gas and oil are distributed over very large volumes of rock, which need stimulation by fracking. Companies have increasingly tapped these formations because they have depleted most of the conventional formations in which gas and oil are contained in a relatively concentrated pool. In these conventional formations, companies can simply perforate the pool with their drill bit and drain a significant quantity of oil or gas. In unconventional formations, however, energy companies must drill more wells because the energy deposits are widely dispersed. Drillers must also use significantly more fracturing fluid to create larger fractures that can access a broader area of oil or gas.
“The rate of drilling and the volume of fluid used have increased tremendously,” said Ingraffea.
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Akhila Vijayaraghavan, writing at Triple Pundit, reports:
This link is not a new one. The USGS already linked about 50 earthquakes in Oklahoma due to fracking. Their investigation found that the earthquakes had a magnitude ranging from 1.0 to 2.8. In January, a single earthquake of the magnitude of 4.0 was strong enough that it was felt in Toronto. The bulk of these occurred within 2.1 miles of Eola Field, a fracking operation in southern Garvin County.
From the report:
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. There have been previous cases where seismologists have suggested a link between hydraulic fracturing and earthquakes, but data was limited, so drawing a definitive conclusion was not possible for these cases.
In April and May, two small earthquakes near Blackpool, in England also contributed to suspicions of a link between earthquakes and fracking. Finally, the company responsible, Cuadrilla Resources, admitted that its shale fracking operations were indeed responsible.
The latest report from USGS states that:
In Oklahoma, the rate of M >= 3 events abruptly increased in 2009 from 1.2/year in the previous half-century to over 25/year. This rate increase is exclusive of the November 2011 M 5.6 earthquake and its aftershocks. A naturally-occurring rate change of this magnitude is unprecedented outside of volcanic settings or in the absence of a main shock, of which there were neither in this region.
Although the report links earthquakes to drilling activities, it is still too early to say whether this is due to the increase in rate of drilling or a specific technique. However the fact remains that it is now an indisputable fact that fracking causes abnormal seismic activity. This definitely puts the oil and gas industry as the most environmentally damaging enterprise. The sooner we are able to switch to more renewable sources of energy, the better.
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