Fracking responsible for 22,900 percent increase in Oklahoma earthquakes since 2008
A study published in July 4, 2014 issue of Science determined that the surge in earthquake activity in what had been tectonically calm Oklahoma is a direct result of hydrofracking and waste-water injection.
Before 2008, Oklahoma averaged one earthquake with a magnitude of 3.0 or greater every year. To date in 2014, the state has witnessed more than 230 such tectonic events.
One of the study’s co-authors, Cornell University’s Geoffrey Abers, told Nature that “it is really unprecedented to have this many earthquakes over a broad region like this.”
“Most big sequences of earthquakes that we see are either a main shock and a lot of aftershocks or it might be right at the middle of a volcano in a volcanic system or geothermal system,” he added, “so you might see little swarms but nothing really this distributed and this persistent.”
Abers and his colleagues analyzed the data on rate and volume of liquids being used in waste-water injection sites and compared it to the physical properties of the rock into which it was injected. They found that a small number of waste-water injection sites could be responsible for the large increase in earthquake activity state-wide.
“The risk of humans inducing large earthquakes from even small injection activities is probably high,” Abers said about a 5.7 magnitude earthquake in Prague, Oklahoma in March. Now he has evidence proving that “[s]ome of these earthquakes are as much as 20 miles away from what seems to be the primary wells that are increasing the pressure.”
Researchers believe that the earthquakes are caused by “overpressuring” a fault system. Injecting too much waste-water into the ground causes tectonically stable areas to “slip,” resulting not only in a single earthquake, but a redistribution of pressures along the entire fault system — which is what Abers and his team believe is happening Oklahoma.
“I think this rate of earthquake increase in the midcontinent is really extraordinary and is continuing, but this isn’t the last word on this in any means,” Abers said.