Oklahoma 5.7 earthquake linked to oil extraction wastewater

[Ichingcarpenter]

4. Columbia University

Road damage


Scientists have linked a rising number of quakes in normally calm parts of Arkansas, Texas, Ohio and Colorado to below-ground injection. In the last four years, the number of quakes in the middle of the United States jumped 11-fold from the three decades prior, the authors of the Geology study estimate. Last year, a group at the U.S. Geological Survey also attributed a remarkable rise in small- to mid-size quakes in the region to humans. The risk is serious enough that the National Academy of Sciences, in a report last year called for further research to “understand, limit and respond” to induced seismic events. Despite these studies, wastewater injection continues near the Oklahoma earthquakes.

The magnitude 5.7 quake near Prague was preceded by a 5.0 shock and followed by thousands of aftershocks. What made the swarm unusual is that wastewater had been pumped into abandoned oil wells nearby for 17 years without incident. In the study, researchers hypothesize that as wastewater replenished compartments once filled with oil, the pressure to keep the fluid going down had to be ratcheted up. As pressure built up, a known fault—known to geologists as the Wilzetta fault--jumped. “When you overpressure the fault, you reduce the stress that’s pinning the fault into place and that’s when earthquakes happen,” said study coauthor Heather Savage, a geophysicist at Columbia University’s Lamont-Doherty Earth Observatory.


http://www.earth.columbia.edu/articles/view/3072


Besides poisoning their aquifers their building codes are not up to earthquake building standards such as California and Washington State so human and building damage would be high as compared to the same size quake.

I''m more worried about the lifeblood of the aquifers though both implications of fracking are alarming.