(CN) - Officially linking a controversial natural gas-drilling method to earthquakes for the first time, the U.S. Geological Survey released a groundbreaking report documenting links between fracking and skyrocketing seismic activity.
Released on Monday, the agency's "2016 One-Year Seismic Hazard Forecast" contains no explicit reference to hydraulic fracturing, but the allusion to the process is unmistakable.
"Earthquake rates have recently increased markedly in multiple areas of the Central and Eastern United States (CEUS), especially since 2010, and scientific studies have linked the majority of this increased activity to wastewater injection in deep disposal wells," the 58-page report states.
"Such changes have caused concern to many, including residents, business owners, engineers, and public officials responsible for mitigating or responding to the effects of these earthquakes on nearby populations," it continues.
These "induced earthquakes," as the report calls them, "create seismic hazard to buildings, bridges, pipelines, and other important structures and are a concern for about 7.9 million people living in the vicinity of these events."
Colloquially known as "fracking," hydraulic fracturing extracts natural gas by pumping millions of gallons of a high-pressure slurry comprised of water, sand and chemicals to break apart shale deep in the Earth.
In lawsuits from Arkansas to California, its opponents have long alleged that the technique caused "thousands of quakes" near drilling areas.
Monday's report corroborates many of these allegations with several examples of earthquakes that rocked areas located near injection wells.
In 2011, there was a 5.6-magnitude earthquake recorded near Prague, Okla., a 5.3-magnitude earthquake near Trinidad, Colo., and a 4.7-magnitude earthquake near Guy, Ark., as well as a 4.8-magnitude earthquake near Timpson, Texas.
Though the scientists noted "it is possible that natural earthquakes are ongoing and interspersed with the induced events," their numbers are "probably quite low compared to numbers of induced earthquakes."
"For example, from 1950 to 2005, Oklahoma recorded an average of 1.5 earthquakes with a magnitude greater than 3.0 per year, though some of these earlier earthquakes may also have been induced," the report states. "Over the past few years, however, Oklahoma has recorded several hundred M3.0+ earthquakes per year, many of which are thought to be related to wastewater injection."
The authors of the report include Mark Petersen, Charles Mueller, Morgan Moschetti, Susan Hoover, Andrea Llenos, William Ellsworth, Andrew Michael, Justin Rubinstein, Arthur McGarr, and Kenneth Rukstales.
Mark Peterson, chief of the U.S. Geological Survey's National Seismic Hazard Mapping Project, said in a statement that the new study "shows that much more of the nation faces a significant chance of having damaging earthquakes over the next year, whether natural or human-induced."
The agency typically provides 50-year forecasts of seismic activity, and this report marks its first one-year outlook supplementing the broader reports.
Karthik Ganapathy, a spokesman for the Bernie Sanders presidential campaign, said the report highlights one reason why the Vermont senator supports an all-out ban on fracking.
"Whether it's the disastrous impact of fracking on climate change, the risk of massive disasters like the Porter Ranch gas leak, or its role in inducing more frequent or intense earthquakes, there are lots of reasons to oppose fracking for oil and gas," Ganapathy said in an email. "Bernie Sanders knows that, which is why he's the only candidate in either party who would fight for a ban on fracking as president."
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