After increasing rapidly over the past three years, the pace of earthquakes in Oklahoma held steady in 2014 at a rate higher than California and far higher than the historic average in Oklahoma.
Oklahoma experienced 567 earthquakes of magnitude 3.0 or greater in 2014, up from 209 in 2013. The state had averaged about 40 a year for the previous five years and less than five a year before that.
Despite the rapid increase over the past several years, the rate and severity of earthquakes in Oklahoma has held relatively flat over the past 12 months.
“It looks like we’re at about the same rate now as we were last year at this point,” Oklahoma Geological Society seismologist Austin Holland told The Oklahoman. “We’re continuing to see a high rate, but it looks like a steady rate at this point.”
While researchers and policymakers are pleased the rate has not continued to grow, they are still working to better understand what the state is experiencing.
“We took it as good news, but there are so many unknowns in this,” said Michael Teague, Oklahoma energy and environment secretary. “Until we unravel more of this, I don’t know what to make of the snapshots of data we have now.”
Gov. Mary Fallin in September appointed Teague to lead the state’s Coordinating Council on Seismic Activity.
As the rate of earthquake activity has grown in the state, many homeowners have added earthquake insurance to their existing policies.
About 15 percent of Oklahomans now have earthquake insurance, Oklahoma Insurance Commissioner John D. Doak said. The number is up from about 2 percent in 2011 and outpaces California, where about 10 percent of residents have earthquake insurance.
“We’re continuing to get more and more inquiries,” Doak said. “Gov. Fallin and I have worked together to ensure insurance agents throughout the state now have one hour of continuing education dedicated to earthquake insurance. We’ve found that has been helping. Now licensed brokers are talking about it, and they’re going back and learning about the policies.”
Consumers interested in adding earthquake insurance should speak to their agents and fully read the policies, Doak said.
“Earthquake insurance is affordable and accessible, but you need to understand the terms and conditions in the policy,” he said. “Each policy has different factors. Some things are covered and others are not covered.”
Part of the problem of seeking to determine a cause of the increased activity is that existing earthquake models are based on naturally occurring earthquakes and do not include induced seismically. Researchers still are trying to determine whether or to what extent man-made activity is contributing to the state’s seismic activity.
“There have been occurrences not just in the state, but across the country, where we’ve seen induced seismology,” Teague said. “We’ve seen correlations with injection wells in Ohio and Arkansas, but we haven’t seen that tight correlation in Oklahoma. That’s absolutely one of the struggles.”
Some studies have connected earthquake activity in Oklahoma and other parts of the country to water injection wells used to dispose of water produced along with oil and natural gas. The average oil well in Oklahoma produces about 10 barrels of saltwater for every barrel of oil. For at least 70 years, the oil and natural gas industry has pumped the produced water deep below ground through water disposal wells.
New rules at the Oklahoma Corporation Commission require disposal well operators to more closely monitor volumes and pressures throughout the wells.
To help gain a better understanding of the state’s ongoing earthquake swarm, researchers are installing new seismographs and upgrading existing seismic monitoring equipment throughout the state.
“Our biggest priority is getting the network upgraded so we can say as much as we can about every earthquake that occurs,” Holland said. “That will inform the science in many ways.”
When completed, the network will have about 21 permanent seismic monitors, plus several temporary stations on loan from the U.S. Geological Survey and other groups.
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