US government scientists link shale gas boom to sharp rise in earthquakes
A sharp rise in the number of earthquakes in the US over the past few years is almost certainly caused by human activity and could be linked to a boom in shale gas drilling.
That is the stark finding of a report by the US government’s Geological Survey, due to be launched in full at a conference next week.
The report, produced by a team led by scientist Bill Ellsworth, set out to discover what has caused a six-fold increase in earthquakes in the midcontinent.
Average annual earthquakes rates with a magnitude three or greater jumped from 21 in the three decades before 2000, to 50 in 2009, 87 in 2010 and 134 in 2011.
The scientists now suspect the quakes are caused by wastewater wells, which are a byproduct of oil and natural gas production from tight shale formations and coal beds.
“We’ve been watching the seismicity across most of the country very carefully for a number of years now,” Ellsworth told US news outlet NPR. “One thing we had begun to notice was there was an unusual number of earthquakes occurring in the middle of the country.”
Hydraulic fracturing in shale gas production, also known as “fracking”, uses high pressure water mixed with particles and chemicals to break gas-rich shale rocks apart more than a kilometre underground.
Ellsworth suggested certain locations can more susceptible to earthquakes than others. “Small perturbations can tip the scales, allowing an earthquake that might not otherwise happen for a very long time,” he said.
The report is likely to prompt fresh calls for US officials to step up their policing of shale gas operations and to consider stronger regulations to reduce environmental and health risks that result from fracking projects.
Commenting on the study, David J. Hayes, deputy secretary of the Department of the Interior, agreed that the scientists had found that the increase in seismic activity coincides with the injection of wastewater in deep disposal wells in some locations.
“In preliminary findings, our scientists cite a series of examples for which an uptick in seismic activity is observed in areas where the disposal of wastewater through deep-well injection increased significantly,” he said. “These areas tend to be in the middle of the country – mostly in Colorado, Texas, Arkansas, Oklahoma and Ohio.”
However, he maintained that the study could not blame hydraulic fracturing for the increased rate of earthquakes. He also insisted that it has been known for some time that wastewater wells were a potential cause of earthquakes.
“While it appears likely that the observed seismicity rate changes in the middle part of the United States in recent years are manmade, it remains to be determined if they are related to either changes in production methodologies or to the rate of oil and gas production,” he said.
He added that the Obama administration would continue to research the impact of fracking on seismic activity in order to expand oil and gas production “safely and responsibly” in the US.
That is the stark finding of a report by the US government’s Geological Survey, due to be launched in full at a conference next week.
The report, produced by a team led by scientist Bill Ellsworth, set out to discover what has caused a six-fold increase in earthquakes in the midcontinent.
Average annual earthquakes rates with a magnitude three or greater jumped from 21 in the three decades before 2000, to 50 in 2009, 87 in 2010 and 134 in 2011.
The scientists now suspect the quakes are caused by wastewater wells, which are a byproduct of oil and natural gas production from tight shale formations and coal beds.
“We’ve been watching the seismicity across most of the country very carefully for a number of years now,” Ellsworth told US news outlet NPR. “One thing we had begun to notice was there was an unusual number of earthquakes occurring in the middle of the country.”
Hydraulic fracturing in shale gas production, also known as “fracking”, uses high pressure water mixed with particles and chemicals to break gas-rich shale rocks apart more than a kilometre underground.
Ellsworth suggested certain locations can more susceptible to earthquakes than others. “Small perturbations can tip the scales, allowing an earthquake that might not otherwise happen for a very long time,” he said.
The report is likely to prompt fresh calls for US officials to step up their policing of shale gas operations and to consider stronger regulations to reduce environmental and health risks that result from fracking projects.
Commenting on the study, David J. Hayes, deputy secretary of the Department of the Interior, agreed that the scientists had found that the increase in seismic activity coincides with the injection of wastewater in deep disposal wells in some locations.
“In preliminary findings, our scientists cite a series of examples for which an uptick in seismic activity is observed in areas where the disposal of wastewater through deep-well injection increased significantly,” he said. “These areas tend to be in the middle of the country – mostly in Colorado, Texas, Arkansas, Oklahoma and Ohio.”
However, he maintained that the study could not blame hydraulic fracturing for the increased rate of earthquakes. He also insisted that it has been known for some time that wastewater wells were a potential cause of earthquakes.
“While it appears likely that the observed seismicity rate changes in the middle part of the United States in recent years are manmade, it remains to be determined if they are related to either changes in production methodologies or to the rate of oil and gas production,” he said.
He added that the Obama administration would continue to research the impact of fracking on seismic activity in order to expand oil and gas production “safely and responsibly” in the US.
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