Science 3 min read

Earthquake Hazards: Another Way Oil Extraction Can do Harm

Injecting wastewater underground causes earthquake hazards. A new model predicts the seismic activity associated with wastewater disposal more accurately.

Image courtesy of Shutterstuck

Image courtesy of Shutterstuck

Faults are fractures in rocks deep into the Earth’s crust. They usually can sustain high stresses without slipping, but sometimes human activities create serious earthquake hazards.

Earthquakes are the result of two blocks of rock along a fault that keeps rubbing against each other until they slip and release a burst of energy.

Considering the whole large-scale environmental disruption of oil and gas production, earthquakes that aren’t supposed to happen is another way for fossil fuels to kill us!

The risk of human-made earthquakes is real, and scientists have been working on methods to help them predict the seismic activity induced by the injection of waste fluids more efficiently.

Earthquake Hazards: Beware, Wastewater Injection in the Area!

One of the by-products of oil and gas extraction process is the vast quantities of wastewater that has no other way to go but underground.

Brine injection through deep wells leads to pressure changes that influence the frictional forces between the opposing fault blocks, significantly increasing the chances of them slipping.

Addressing some misconceptions about induced earthquakes, the U.S. Geological Survey (USGS) noted that the disposal of wastewater is the culprit and not fracking. The agency cited that it “is the primary cause of the recent increase in earthquakes in the central United States.”

As drilling for oil and gas continues, deep wastewater disposal will increase, and so is the chances of injection-induced earthquakes.

This led a team of geoscientists from Arizona State University (ASU) to develop a model that could predict seismicity from wastewater disposal.

“Overall, earthquake hazards increase with background seismic activity, and that results from changes in the crustal stress,” said lead researcher Guang Zhai, a postdoctoral research scientist in ASU’s School of Earth and Space Exploration. “Our focus has been to model the physics of such changes that result from wastewater injection.”

Funded by the Department of Energy, the team picked for their study Oklahoma, a state known for the rise in earthquake events in recent years. The increased seismicity in Oklahoma that can’t be explained by natural causes has been linked to the rampant fracking activity and wastewater injection taking place.

Predicting earthquake hazards associated with wastewater injection isn’t easy because it’s subject to too many variables. These include the quantity of wastewater injected, how easily rocks can let the brine through, and the presence of geological faults.

The team built a physics-based earthquake-forecasting model that assesses earthquake hazards induced by wastewater injection. The model combines pore pressure, or the rock’s ability to transport brine; and poroelastic stresses, the rock’s elastic response to brine’s pressure.

The team’s model showed that “the regional induced earthquake timing and magnitude are controlled by the process of fluid diffusion in a poroelastic medium, and thus seismicity can be successfully forecasted by using a rate-and-state earthquake nucleation model.”

“This finding has significant implications for induced earthquake-forecasting efforts by integrating the physics of fluid diffusion and earthquake nucleation.”

The findings of the study are published in the Proceedings of the National Academy of Sciences.

Read More: Scientists Discover GPS Indicator That Could Signal A Coming Megaquake

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Zayan Guedim

Trilingual poet, investigative journalist, and novelist. Zed loves tackling the big existential questions and all-things quantum.

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