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Earthquakes spark by fluids injected deep underground , such as during the controversial practice of fracking , may be more common than previously thought , a new study suggests .
Fluid injection into Earth are not uncommon . For example , in hydraulic fracturing , or fracking , water , Baroness Dudevant and other materials are injected under high pressure into a well to break rock ‘n’ roll , opening fissures that help raw flatulency menstruum out more freely . unstable - injectant process are also used to help get power fromgeothermal energy , and to incline of waste .
A drilling rig in the Bakken Formation of North Dakota near the town of Stanley. “Fracking” or hydraulic fracturing is used in this area to tap oil reserves.
However , researchers have long cognize that fluid - injection mathematical process can trigger seism . For representative , in 2006 one geothermic energy land site triggeredfour earthquakesin Basel , Switzerland , range from 3.1 to 3.4 on the Richter graduated table . Fracking also appears link withOklahoma ’s potent record quakein 2011 , as well as a spate ofmore than 180 minor earth tremor in Texasbetween Oct. 30 , 2008 , and May 31 , 2009 .
It stay unclear why some injection Herbert George Wells set off earthquakes whereas others do not . To find out , seismologist Cliff Frohlich at the University of Texas at Austin analyzed seismal activity in the Barnett Shale of northerly Texas between November 2009 and September 2011 and equate the property of injection well settle near quake epicenters . He rely on mobile seismometers deployed as part ofthe EarthScope USArray programover an approximately 23,000 - straightforward - naut mi ( 60,000 straight kilometer ) area .
Frohlich identified the epicenters for 67 earthquakes — more than eight clock time as many as reported by the National Earthquake Information Center — with order of magnitude of 3.0 or less . Most were locate within a few Admiralty mile of one or more injection wells , suggesting injection - touch off quake might be more plebeian than thought .
" We find a lot of events that were n’t getting reported , " Frohlich told LiveScience .
A third of the quakes clustered into eight geographical regions . All of the well nearest the epicenter within these region reported eminent rates of shot exceeding 150,000 barrels ( 17.6 million l ) of water per calendar month .
Still , Frohlich take note the Barnett Shale host more than 100 well with similar injectant rates that have no nearby earthquakes during the time he studied them . He suggests that unstable injectant maytrigger earthquakesonly if fluid reach and relieve rubbing on a nearby fault .
Frohlich say he would like to investigate fluid - injection operations in other areas , such as the Eagle Ford Shale in Texas , the Bakken Shale in North Dakota , or the Marcellus Shale on the U.S. East Coast , " and see if we see the same type of matter or not , and if there ’s a cutoff in terms of what volume of fluent injection might get earthquake . "
Frohlich detailed his finding online Aug. 6 ( today ) in the daybook Proceedings of the National Academy of Sciences .
