In response to an ongoing rash of earthquakes, the Oklahoma Geological Survey has installed new monitoring stations throughout the state and earlier this month hired another seismologist.
At least six magnitude 2.5 or greater earthquakes were recorded near Guthrie on Tuesday after a series of quakes in the area over the weekend. The rattling continues a streak of more than 300 such quakes throughout the state over the past two years.
“We’re working as fast as we can, including nights and weekends,” seismologist Austin Holland said. “We certainly understand that people want answers. We’re trying to get those as quickly as we can.”
The geological survey recently installed additional seismographs throughout the state, including one near Guthrie. The equipment helped determine the most recent quakes have occurred along a different fault from previous quakes, including those near Jones and east of Edmond.
“This fault is one likely to have naturally occurring earthquakes on it,” Holland said.
There were no active hydraulic fracturing activities in the area, but the survey is studying whether water injection wells could have contributed to the most recent and other quakes throughout the state, Holland said.
“We’re still looking at that as a possibility, but we’re waiting for data,” he said. “Those determinations can take a very long time to complete.”
While it is still unclear what is causing Oklahoma’s earthquakes, part of the investigation has centered on whether water injection wells could be contributing. It also is possible that the recent quakes are a result of natural causes, Holland said.
Water injection wells have been connected to earthquakes in Ohio and other isolated parts of the country.
On average, wells in Oklahoma produce about 10 barrels of saltwater for every barrel of oil they release. Some of the state’s rocks — including northern Oklahoma’s Mississippian formation — produce up to twice that volume of water.
The produced water usually is returned deep underground through disposal wells designed to handle high pressure and large volumes of water.
Injection and disposal wells have been used throughout Oklahoma for much of the state’s history. While oil and natural gas activity has picked up in Oklahoma in recent years, oil and water production still pale compared to levels seen in the 1980s and 1920s.
Most modern wells are drilled using hydraulic fracturing, or fracking, which uses sand and large volumes of water to shatter rock and stimulate production.
“Hydraulic fracturing contributes a very small amount of the volumes of water injected in the state,” Holland said. “The greatest contributor is produced water. That’s been going on for a long time.”
While the investigation continues, the Oklahoma Corporation Commission is working with the Oklahoma Geological Survey, oil companies and water disposal well operators to develop best practices, which could eventually become new rules.
The commission is scheduled to discuss the rules at two technical conferences Wednesday.
Commissioner Dana Murphy said she hopes to have the proposed rules to the Legislature by April. If approved, the rules likely would become effective July 1.
“You have to collect the data and do the research to study if there are connections,” between the disposal wells and the quakes, Murphy said. “The issue is how do we find a connection and what do we do if there is one. We have to have the data to make sure we’re taking appropriate consideration before taking action.”
AT A GLANCE
greater than magnitude 2.5
•2.7: 6 miles southeast of Medford at 8:22 a.m.
•2.8: 6 miles southwest of Guthrie at 6:29 a.m.
•3.3: 5 miles southwest of Guthrie at 6:16 a.m.
•3.8: 7 miles south of Guthrie at 5:53 a.m.
•2.6: 12 miles southwest of McCord at 1:15 a.m.