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Saturday quake biggest ever in Okla.; more may be on way

Employee Talia Pershall, 16, puts syrup back on a shelf while cleaning up at White’s Foodliner grocery store on Saturday in Pawnee, Okla., after a 5.6 magnitude earthquake in north-central Oklahoma.
Employee Talia Pershall, 16, puts syrup back on a shelf while cleaning up at White’s Foodliner grocery store on Saturday in Pawnee, Okla., after a 5.6 magnitude earthquake in north-central Oklahoma. Associated Press

U.S. Geological Survey researchers say they’re upgrading the strength of an Oklahoma earthquake that struck over the weekend to a 5.8 magnitude, making it the most powerful earthquake ever recorded in the state.

Survey research geophysicist Daniel McNamara said Wednesday the previous strongest recorded quake in Oklahoma – a 5.6-magnitude temblor in 2011 – also is being upgraded to a 5.7-magnitude quake.

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Saturday’s earthquake centered near the north-central town of Pawnee damaged more than a dozen buildings and left one man with a minor head injury after a fireplace collapsed.

Another earthquake of a magnitude 5.0 or greater could shake northern Oklahoma within the next month and there’s a 29 percent chance within the next year, according to geologists with the survey.

The scientists’ estimate is based on what the response has been after other big earthquakes that have had a similar pattern of aftershocks as the one on Saturday that was strongly felt in Wichita.

There were four aftershocks immediately after the earthquake near Pawnee, Okla., with the largest being a 3.6. In the past 24 hours – beginning Tuesday evening – Oklahoma has had five additional earthquakes, the largest being a magnitude 3.5.

The geological survey warned that there is the possibility of additional earthquakes capable of doing damage. It put the chance of an aftershock of magnitude 5 or greater in the Pawnee area at 12 percent within the next month.

Saturday’s temblor was only the third earthquake measured at a magnitude 5 or greater since the exponential rise in Oklahoma and Kansas earthquakes since 2009, according to the survey.

Oklahoma and Kansas have had about 80 earthquakes with a magnitude of 4 or higher in that time period.

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The vast majority of earthquakes in this area have been determined to be caused by humans but it would take additional research to definitively say whether any particular earthquake was caused by humans, according to the survey.

In addition to pumping millions of tons of waste water and chemicals into the ground, the survey noted that some other possible causes of the earthquakes could be “fluid withdrawal, enhanced oil recovery, or hydraulic fracturing processes.”

Federal seismologist Justin Rubinstein, speaking at the Kansas Cosmosphere on April 30, 2016, said the state is seeing fewer earthquakes, in part because of state mandates. But more regulations are being looked at and the state remains among the m

(FILE VIDEO)

Contributing: Associated Press

Oliver Morrison: 316-268-6499, @ORMorrison

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