Yuuuuuge 5.0 Earthquake Rocks Giant Oil Hub In Oklahoma
There she goes again. Just two months after the US Geological Survey reported the largest ever earthquake in Oklahoma, on Sunday Mother Nature struck again. This one clocked in at 5.0 and it was centered uncomfortably close to the city of Cushing, which happens to be the site of one of the world’s largest oil terminals.
News reports are already linking this latest temblor to the practice of disposing oil and gas wastewater in wells, so actually Mother Nature may be off the hook for this one.
Oklahoma Earthquakes And Mother Nature
For those of you new to the topic, Oklahoma was formerly a quiet state, seismically speaking. That has changed dramatically in recent years. The state has been experiencing swarms of earthquake activity, topped by a record-setting 5.8 quake that hit the City of Pawnee on September (the quake was initially measured at 5.6 but revised upward upon further analysis).
How bad is it? Well, Oklahoma has been outpacing the notoriously active state of California, and last year it earned the dubious honor of being the Earth’s number one spot for seismic activity.
USGS researchers are among those who have linked the state’s unwanted seismic status to the use of injection wells for disposing wastewater from oil and gas operations.
Deep well injection is a longstanding practice for conventional oil and gas drilling. More recently, large volumes of wastewater have been contributed by the boom in fracking (short for hydrofracturing, a method for extracting oil and gas from shale formations).
The numbers are significant. According to a Stanford University research team, in 1997 a total of about 20 million barrels of wastewater was disposed in Oklahoma wells. By 2013, that figure had jumped to 400 million.
The spike in wastewater disposal has had dramatic consequences for Oklahoma. Seismologists attribute the phenomenon to the unique characteristics of the Arbuckle formation underlying the surface. Here’s an explainer from Stanford:
…wastewater disposal is increasing the pore pressure in the Arbuckle formation, the disposal zone that sits directly above the crystalline basement, the rock layer where earthquake faults lie. Pore pressure is the pressure of the fluids within the fractures and pore spaces of rocks at depth…
Increased pore pressure leads to a buildup of shear stress, which eventually becomes strong enough to overpower the frictional force that holds the two sides of a fault in place.
In effect, wastewater disposal has been revving up a natural process that would normally lead to an earthquake every “few thousand” years.
The evidence of a disposal well linkage has been conclusive enough to convince state officials to take action.
In the latest development, following the September 3 quake Governor Mary Fallin ordered the emergency shutdown of disposal wells in Pawnee County.
Too Little, Too Late For Oklahoma Earthquakes
Despite the disposal well closures, earthquake activity has continued apace in Oklahoma.
Sunday’s quake, fortunately, did not result in any reported injuries. However, local reporting by News9.com paints a picture of “significant damage” to downtown Cushing.
Emergency shelters were opened, the downtown area was evacuated upon reports of gas leaks, and schools and other public buildings were ordered closed for Monday pending damage assessments.
CBS adds some detail:
The U.S. Geological Survey reported the earthquake struck at 8:44 p.m. EST, with an epicenter located one mile west of Cushing.
The quake was felt as far away as Kansas City, Missouri, and Little Rock, Arkansas. It was also felt in Iowa, Illinois and Texas.
This map shows where USGS received “Did You Feel It?” reports:
As for the “pipeline crossroads of the world,” according to CBS‘s reporting, operators of the Cushing hub have not found any signs of damage.
Meanwhile, the earthquake activity has spurred a lawsuit brought by the Pawnee Nation against Sandridge Exploration and Production, Chesapeake Operating and Devon Energy Production Company.
If Sandridge rings a bell, that company was a holdout last year when Governor Fallin began calling for voluntary curbs on disposal wells. Chesapeake Operating comes under the Chesapeake Energy umbrella, which is already in hot water for allegedly rigging oil and gas leases.
Rounding out the trio, Devon contributed the advice of its founder and former CEO Larry Nichols to Florida Senator Marco Rubio’s failed run at the Republican presidential nomination. Among other activities on behalf of his industry, Nichols reportedly pumped $200,000 into the effort to prevent Denton, Texas, from prohibiting fracking within city limits.
In Oklahoma, Pawnee leaders have pointed out that the City of Pawnee is not empowered to ban injection wells, but the Pawnee Nation could take action on lands under its jurisdiction.
Last year the tribe’s business council passed a resolution asking for a moratorium on both fracking and wastewater injection, and requesting the Bureau of Indian Affairs to start planning for the protection of Pawnee water rights.
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Images (screenshots, enhanced for readability): via USGS.
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