OKLAHOMA CITY — While the overall number of earthquakes skyrockets in Oklahoma, the new director of the state Geological Survey says there has been a modest decline over the last three months.
Jeremy Boak, hired in June to head the agency that studies geology and mineral resources, was one of several experts who testified Friday about the increase in earthquakes before a joint House and Senate committee. The rise has been linked to disposal wells where wastewater from oil and gas production is injected deep underground.
Boak says the average number of earthquakes of magnitude 2.8 or higher recorded in Oklahoma has dropped from five per day to 3.5 per day over the last 90 days. A dramatic drop in the price of oil over the last year has led to a decline in oil and gas drilling activity, and regulators have taken new steps to control wastewater wells, but Boak said it’s too early to draw any scientific conclusions.
“Something is happening. We’re not quite sure how to explain it,” Boak said. “It’s not time to declare victory by any means, but it is an interesting development.”
Despite the trend, the overall number of earthquakes has gone from a few dozen that were magnitude 3.0 or greater in 2012, to 109 in 2013, 584 in 2014 and 722 this year as of Friday afternoon.
The uptick in the number of quakes has prompted the Oklahoma Corporation Commission, which regulates the oil and gas industry, to direct operators to shut down dozens of disposal wells and adjust the volume of wastewater or depth at many others.
A recent spate of earthquakes in the area surrounding Cushing, a delivery point for most of the oil traded in the U.S., had officials with the U.S. Department of Homeland Security concerned, said Michael Teague, the state Secretary of Energy and Environment.
“The tanks, certainly the post-1970 tanks, have been built specifically for seismic forces,” Teague said. “The pipelines and pipeline control is very similar.” But, he added, recent inspections showed no damage.
The strongest earthquake on record is a magnitude 5.6 centered in Prague in November 2011 that damaged 200 buildings and shook a college football stadium. And Boak says data suggests there is a 42 percent chance of a 5.5-magnitude quake occurring in Oklahoma within the next four years, while the chance for a magnitude 5.0 quake within the next year is greater than 50 percent.
“The idea that we have such a high likelihood of a magnitude 5 is concerning,” Boak said. “It’s sobering.”
But Rep. Corey Williams, a Stillwater Democrat whose district has seen a dramatic increase in seismic activity, has grown frustrated by the Republican-controlled Legislature’s lack of action to impose regulations on the oil and gas industry.
“We’ve got 40 to 50 million barrels of crude sitting above ground in those storage tanks (in Cushing),” Williams said. “I don’t want a domino effect of tanks coming down out there or pipeline ruptures going on. I certainly don’t want any loss of life, and I’d prefer not to have an environmental catastrophe as well.”
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