The fracking process includes having to dispose of millions of gallons of fracking wastewater by injecting it deep into the earth. For example, fracking wastewater from southwestern Pennsylvania fracking operations is transported over to Ohio to be disposed of there. The question re huge increase in the number of Oklahoma earthquakes was whether that could be linked to the massive injection of wastewater in the Oklahoma area. A scientific study of the record-breaking 2011 Oklahoma earthquake was just published last month and detailed the link between fracking injection wells and earthquakes. It concluded that injection wells used by the oil and gas industry were the cause of a new type of induced earthquake.
The report’s lead author, University of Oklahoma seismologist Katie Keranen, focused on a series of earthquakes in November 2011 near Prague, Okla., including a 5.7-magnitude temblor on Nov. 6, the largest recorded in state history. The quake destroyed 14 homes, buckled pavement and was felt in 17 states, according to the report. Prague lies near a fault line and oil fields where injection wells have been used for decades.
More than 1,400 earthquakes were recorded in Oklahoma in 2011, the most active year on record. At the same time, seismic activity also increased throughout the middle of the country, with quakes reported in Arkansas, Colorado, Ohio and Texas.
ttp://www.latimes.com/news/nation/nationnow/la-na-nn-oklahoma-quakes-fracking-20130327,0,7788391.story
The same year, regulators in Arkansas banned injection wells from a region that stretches across the state that had been shaken by a series of quakes. Oil and gas regulators in Colorado require review by a state seismologist before permitting injection wells, and Illinois has installed a traffic light system to stop injection wells if related earthquakes appear to put public safety at risk.
Oklahoma’s largest-recorded earthquake was triggered by injection wells used by the oil and gas industry, according to a report released this week. The Tuesday report in the geoscience journal Geology is the latest scientific evidence suggesting injection wells may be causing an uptick in earthquakes nationwide. However, the report was viewed skeptically by Oklahoma's official seismologist.
The report suggests that injection-induced earthquakes could be larger than previously thought, and could take much longer periods of time to be triggered. “This is basically a different class of induced earthquake,” Keranen told NPR.
Keranen’s report, written with Columbia University’s Heather Savage and Geoffrey Abers, and the U.S. Geological Survey’s Elizabeth Cochran — is based on data collected from more than a dozen seismometers in Oklahoma during the so-called “Prague Earthquake Sequence” and data collected by the state’s oil and gas regulator, the Oklahoma Corporation Commission.
Researchers from Oklahoma and Columbia universities found that over time, depositing used-up drilling fluid into the ground may have snapped geological tension that had built up near rural Prague, Oklahoma, causing a 5.7 quake that destroyed 14 homes and injured two.
The authors also write that the number of large earthquakes in and around the center of the country has skyrocketed in recent years.
Here's exactly how they put it: Earthquakes with Mw ≥ 5.0 [larger than 5.0 on the Richter scale — ed.] are rare in the United States east of the Rocky Mountains; however, the number per year recorded in the midcontinent increased 11-fold between 2008 and 2011, compared to 1976–2007. Of the total seismic moment released in the region, ~66% occurred in 2011 (from the GCMT).
This echoes findings from a 2012 USGS study that found the frequency of earthquakes greater than or equal to Mw 3.0 had picked up six fold between 2001 and 2011 compared to the average for the 20th century.
Read more:
http://www.businessinsider.com/fracking-wastewater-oklahoma-earthquake-2013-3#ixzz2Qe7hDnuv
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