A U.S. Geological Survey scientist Friday said large earthquakes in unusual places like Virginia and southern Colorado earlier this week aren’t typically associated with the controversial natural gas drilling process called hydraulic fracturing.

“That process can cause very small earthquakes, but the fracking process doesn’t really, we think, induce large earthquakes,” USGS scientist Mike Blanpied said on a video chat. “The thing that can induce larger earthquakes is the high-pressure waste fluid injection that’s done in some places.”

Blanpied was answering questions from the public in the wake of Tuesday’s 5.8-magnitude earthquake in Louisa County, Va., and Monday’s 5.3-magnitude earthquake in Las Animas County, Colo.

Questions have been raised about the possible connection between earthquake swarms and fracking – a process in which water, sand and often undisclosed chemicals are injected under high pressure deep into natural gas wells to fracture tight geological formations and free up more gas. Fracking occurs in about 90 percent of all natural gas wells in the United States.

The fluids are often brought back up and stored on the surface for re-use and later disposed of in separate deep-injection wells. And it’s those disposal wells that in the past have prompted investigations by the USGS after rare earthquake swarms in southern Colorado, where in 2001 officials said they could “not rule out the possibility” the wells caused the quakes.

Tuesday’s Virginia earthquake, felt in Washington, D.C., and farther north along the East Coast, was not in a heavy gas-drilling area but is fairly close to the border of West Virginia, a state with major coal-bed methane reserves and a great deal of drilling and mining activity.

“However, as far as we’re aware, there’s not really the mining or the fluid injection processes going on in Virginia that would have connected this earthquake with anything like that,” Blanpied said Friday. “Just to be clear, the connection between fracking and fluid injection and earthquakes is an area of active research and really we’re only starting to learn about how those things are connected.”

Last month, the Arkansas Oil and Gas Commission identified four disposal wells it says need to be shut down in the wake of earthquake swarms in that state last spring. The state also ordered a moratorium on new disposal wells in the area.

The USGS cites a Colorado case in the 1960s as the most famous example of deep-injection wells causing an earthquake.

“The largest and most widely known resulted from fluid injection at the Rocky Mountain Arsenal near Denver, Colo.,” the USGS states. “In 1967, an earthquake of magnitude 5.5 followed a series of smaller earthquakes. Injection had been discontinued at the site in the previous year once the link between the fluid injection and the earlier series of earthquakes was established.”

The U.S. Army had been disposing of toxic fluids at depths of nearly 12,000 feet but had to discontinue the process after the quakes.

Some gas-drilling proponents say the concern about fracking, fluid disposal and earthquakes is yet another attempt by the environmental community to sound unwarranted alarms about the industry.

Although she was speaking before the Colorado and Virginia quakes and not addressing those specific concerns, Colorado Oil and Gas Association President and CEO Tisha Schuller recently told an energy conference in Aspen that public concern about fracking — blasted by some on the Western Slope for potentially contaminating groundwater supplies — is akin to skepticism by others about climate change.

“In the same way that the climate movement has to deal with this unimaginable conflict about people not believing in science, we have to do that in the conversation about hydraulic fracturing,” Schuller said, according to the Aspen Daily News. “And the nature of the conversation is as important as the information … The public must be willing to hear that it’s safe when it’s demonstrated.”

Editor’s note: Colorado Independent Western Slope environment and energy reporter David O. Williams discussed this topic with guest host David Sirota on the nationally syndicated Randi Rhodes radio show on Thursday.



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