The 585 earthquakes that Oklahoma had in 2014 was a lot. But this year, Oklahoma has had more than that in less than eight months.
About 20 minutes before midnight Monday, Oklahoma topped last year's total with its 586th earthquake of magnitude 3 or greater. Oklahoma Geological Survey (OGS) data indicate that a magnitude-3.3 quake about 20 miles east of Enid was the one that broke the record.
The state has averaged 2.5 quakes a day in 2015. If that rate continues, Oklahoma would have more than 912 quakes this year.
California has had fewer than 90 quakes this year, so Oklahoma has had more than six times as many.
The unprecedented seismic swarms appear to be the result of favorably aligned faults and oil production methods that create uniquely large volumes of wastewater.
OGS earlier this year joined the scientific consensus that the sharp spike in earthquakes there is due to oil and gas activity, namely wastewater disposal (Greenwire, April 21). The fluid gets into faults, lubricating them, which can unleash quakes.
Oklahoma Gov. Mary Fallin (R) recently said that homeowners in the state should consider buying earthquake insurance to protect their property from the rumbling.
She said the efforts undertaken by the state to lessen quakes could take more than a year to have any effect.
Oil and gas regulators at the Oklahoma Corporation Commission have focused on ensuring that disposal wells in quake-prone areas are not drilled so deep that they penetrate granite bedrock. Scientists say injecting into such "basement rock" raises the risk of quakes. But recently the commission also ordered well operators in an area north of Oklahoma City to cut the volume they inject by 38 percent, back to 2012 levels.
From 1975 to 2008, the state averaged about two quakes a year of magnitude 3 or greater. The number started growing in 2009, when there were 20 such quakes. By 2011, there were 63, including a magnitude-5.6 quake near Prague that caused significant damage. In 2012, the number went over 100.
The state Legislature didn't pass any bills addressing seismicity during its most recent term. Instead, it finalized a bill that prevents cities from regulating most aspects of oil and gas production, and it cut the budget for the Corporation Commission.
Leaders of Oklahoma's oil and gas industry have interfered with the state's research into the shaking. State scientists suspected that oil and gas activity was the culprit for some seismicity as early as 2007. When OGS did cautiously join with outside scientists in a 2013 statement linking quakes and disposal, the state seismologist was called into a meeting with University of Oklahoma President David Boren and Continental Resources Inc. founder Harold Hamm (EnergyWire, March 3).
Later, Hamm told the college dean who oversees OGS that "he would like to see select OGS staff dismissed" (EnergyWire, May 20).
Standard & Poor's recently reported that the increase in quakes in drilling areas represents "a risk that could harm investors across various sectors."
Most of the quakes that can be felt in Oklahoma are not due to hydraulic fracturing. Wastewater specifically from fracturing does get injected into disposal wells. But it's only a fraction of the significant increase in fluid injected in earthquake-prone areas.