Fracking earthquakes: despite mounting evidence, Oklahoma geological survey downplays risks

OKLAHOMA CITY - Of the fourteen 4.0 magnitude earthquakes or higher recorded in Oklahoma, ten of them have occurred in the past four years. Between the years of 1975 and 2008 an average of one to three earthquakes of 3.0 magnitude or larger occurred annually. From 2009 onwards the state has experienced over 200 earthquakes of magnitude 3.0 or higher, an average of more than 40 per year. Several of them have centered near the most populated part of the state, central Oklahoma. In addition, in 2013 Oklahoma experienced 99 earthquakes which measured 3.0 or greater, the second largest in the U.S. behind California...

In October of 2013, Dr. William Leith, Senior Science Advisor for Earthquake and Geologic Hazards for the U.S. Geological Survey (USGS) issued the following statement concerning the uptick of seismic activity in Oklahoma: “We've statistically analyzed the recent earthquake rate change and found that they do not seem to be due to typical, random fluctuations in natural seismicity rates.” ...

The use of disposal wells for wastewater injection, a common practice used in fracking, but also in other more “traditional” extraction techniques, has been positively linked to the increase in both rate and magnitude of earthquakes across the United States in Colorado, Ohio, Oklahoma, and Texas as well as across the globe in both Canada, and the United Kingdom. In addition, ongoing studies suggest manmade links to increased seismicity in Arkansas and Kansas...

Nevertheless, while researchers from the USGS and a significant amount of peer-reviewed geological studies have linked the increase in both rate and size of earthquakes in Oklahoma and other parts of the country to the oil and gas industry, the OGS (Oklahoma Geological Survey) remains reluctant to attribute the increase to anthropogenic causes.

The largest recorded earthquake in the state’s history, a 5.6 magnitude earthquake that produced 10 aftershocks, could be felt across several states and occurred on November 6, 2011. A study published in the journal Geology positively linked injection wells with this earthquake and its subsequent aftershocks...

In response to that study, the OGS issued a statement on their website stating, "The interpretation that best fits current data is that the Prague [Oklahoma] Earthquake Sequence was the result of natural causes.”

Dr. Elizabeth Cochran, a researcher from the USGS and one of the other co-authors of the Oklahoma study was asked about the statement issued by the OGS and responded saying, “that was just a statement they issued on their website. And this was not in a peer-reviewed article. And so we really don't have much of a response to that, because we're not sure what they're basing that observation on.”...

The OGS is not the only agency or group of geologists to reject a close causal link between disposal wells and increased seismicity. However, among the experts who have studied the issue and published papers, the meta-analysis is clear: Disposal wells used in hydraulic fracturing can trigger large earthquakes...

Read the full article at: http://www.reddirtreport.com/red-dirt-news/fracking-earthquakes-despite-mounting-evidence-oklahoma-geological-survey-downplays