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A magnitude 5.2 earthquake struck West Texas early Wednesday near the border of Reeves and Culberson counties, according to the US Geological Survey.
The quake, which struck about 4:30 a.m. northwest of central Pecos, was the fourth-strongest on record in Texas, according to the Bureau of Economic Geology at the University of Texas at Austin, and could be felt as far away as El Paso and Roswell, New Mexico.
The number and magnitude of earthquakes in West Texas has increased dramatically after years of hydraulic fracturing activity in the region. The routine practice of injecting the contaminated, salty water that comes out during the oil production process deep underground has been linked by scientists to an increase in seismic activity in oil fields.
Years of pumping millions and millions of gallons of so-called produced water back underground as a disposal method likely increased the pressure and awakened ancient fault lines, scientists told the Tribune.
There are nearly 80 injection wells in the Culberson County and Reeves County areas, according to data from the Railroad Commission of Texas, which regulates the state’s oil and gas industry.
The quake is the second earthquake of magnitude 5.0 or greater to hit the area in just over a year. Such strong earthquakes in Texas were rare, scientists said.
“It’s not just this earthquake,” said Alexandros Savaidis, senior research fellow in the Bureau of Economic Geology at UT-Austin.
He pointed to a recent magnitude 4.0 earthquake that struck the same region in late August and several other earthquakes of magnitude 3.5 or greater that shook Culberson and Reeves counties in the summer and fall.
“In the last few months, there have been other earthquakes and seismicity that has increased again,” Savaidis said.
In late 2021, state regulators determined that an “unprecedented frequency” of significant earthquakes in Culberson and Reeves counties was likely caused by injecting salt water underground.
The state railroad commission has ordered companies in the region to create a plan to reduce the amount of water they inject underground in that area.
The plan was to ensure that the frequency of earthquakes of magnitude 3.5 or higher decreases after 18 months, which would be in September.
A railroad commission inspector was sent to the area Wednesday to inspect disposal wells in the area, according to RJ DeSilva, a spokesman for the commission.
“The RRC is working with operators in the area to limit the volumes of produced water injected into disposal wells to reduce the intensity and frequency of earthquakes in the region,” DeSilva said. He added that the agency will decide whether to take further action based on inspections, data and meetings with oil field operators and the Bureau of Economic Geology at UT-Austin.
Still, Justin Rubinstein, a research geophysicist with the US Geological Survey, said he doesn’t necessarily expect the number and strength of earthquakes to decrease in the area even as water injection slows.
“Obviously, the changes have not yet resulted in a reduced frequency of earthquakes,” Rubinstein said.
Other areas where water injection has caused seismic activity show that earthquakes can continue for years after the injection stops, he said.
“We can make predictions, but the Earth is incredibly complex,” he added.
After a magnitude 5.4 earthquake last November, railroad commission officials expanded the area where injections would be restricted and asked companies to further reduce the volume of water injected underground in the area to 162,000 barrels per day, or about 6.8 million gallons per day. That’s a 68 percent decrease from the volume injected in January 2022, according to the agency.
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