“Study suggests earthquakes are triggered well beyond fluid injection zones” – Tufts University

News Release, Tufts University 5/3/19

“Using data from field experiments and modeling of ground faults, researchers at Tufts University have discovered that the practice of subsurface fluid injection used in ‘fracking’ and wastewater disposal for oil and gas exploration could cause significant, rapidly spreading earthquake activity beyond the fluid diffusion zone. Deep fluid injections — greater than one kilometer deep — are known to be associated with enhanced seismic activity—often thought to be limited to the areas of fluid diffusion. Yet the study, published today in the journal Science, tests and strongly supports the hypothesis that fluid injections are causing potentially damaging earthquakes further afield by the slow slip of pre-existing fault fracture networks, in domino-like fashion.”

“Most earthquakes induced by fracking are too small — 3.0 on the Richter scale — to be a safety or damage concern. However, the practice of deep injection of the waste products from these explorations can affect deeper and larger faults that are under stress and susceptible to fluid induced slippage. Injection of wastewater into deep boreholes (greater than one kilometer) can cause earthquakes that are large enough to be felt and may cause damage.”

“According to the U.S. Geological Survey, the largest earthquake induced by fluid injection and documented in the scientific literature was a magnitude 5.8 earthquake in September 2016 in central Oklahoma. Four other earthquakes greater than 5.0 have occurred in Oklahoma as a result of fluid injection, and earthquakes of magnitude between 4.5 and 5.0 have been induced by fluid injection in Arkansas, Colorado, Kansas and Texas.”

“This work was supported by grants from the U.S. Geological Survey (USGS #G17AP00016), the National Science Foundation (NSF #EAR-1653382), and the Southern California Earthquake Center (SCEC).” 

Please see further information about this study and a map of regions of high human-induced quake activity, including those in Colorado, in the news release here.
https://now.tufts.edu/news-releases/study-suggests-earthquakes-are-triggered-well-beyond-fluid-injection-zones