The 4.7 magnitude temblors felt last Sunday in Arkansas, part of a recent “swarm” of earthquakes in the area, could be just a prelude to something much more devastating. The threat would be lessened if oil and gas companies are barred from injecting post-fracking wastewater into the earth.
Arkansas once had an earthquake so big it caused the Mississippi river to run backwards.
There are several faults in Arkansas including one not far from the site of the most recent quake. Two hundred years ago, one of these faults, the New Madrid fault, caused a series of quakes so gigantically devastating that they caused the Mississippi river to temporarily reverse direction.
Acres of cotton fields cover the new-found fault west of Marianna, about 100 miles (161 kilometers) east of Arkansas’s capital, Little Rock. But stretches of fine sand mixed with fertile soil gave away the fault’s location, says Haydar Al-Shukri, the director of the Arkansas Earthquake Center at the University of Arkansas at Little Rock.
The previously unknown fault, likely created in the last 5,000 years, ould trigger a magnitude 7 earthquake with an epicenter near a major natural gas pipeline. Such temblors cause massive destruction in their wake.
“This is a very, very dangerous [area] at risk of earthquake,” Al-Shukri said. “When you talk about [magnitude] 7 and plus, this is going to be a major disaster.”
Arkansas has an extensive network of natural gas pipe lines. Even if a devastating but entirely natural quake occurred in the area, the extensive gas pipeline infrastructure criss-crossing the state would be at risk.
Rebecca Virden, a spokesperson for CenterPoint Energy Inc., which owns Arkla, said Wednesday that the company worked closely with public officials to prepare response plans for earthquakes and other natural disasters.
Pipes are “all over the place,” Virden said. “We, CenterPoint Energy, or someone else has a pipeline everywhere.”
Earthquakes aren’t just a side effect; they’re literally how the process of fracking for natural gas works!
Fracking, or hydraulic fracturing, requires that you inject fluid at high pressure deep into rocks in order to split them asunder. The micro-earthquakes this process causes are how you know it’s working. Generally, they’re too slight for anyone to feel. The United States Geological Survey doesn’t think the production wells used for fracking in the Arkansas are causing the most recent large earthquakes. Rather, they think the problem is “re-injection” wells, in which fracking wastewater is forced under pressure into the ground beneath small towns.
In Switzerland and Germany, efforts to use hydraulic fracturing to crack open the earth in order to create below-ground heat exchangers suitable for use as reservoirs of hot water for geothermal power production have caused extensive earthquakes, many severe enough to halt production altogether.
On December 8, 2006, Markus Häring caused some 30 earthquakes — the largest registering 3.4 on the Richter scale — in Basel, Switzerland. Häring is not a supervillain. He’s a geologist, and he had nothing but good intentions when he injected high-pressure water into rocks three miles below the surface, attempting to generate electricity through a process called enhanced geothermal.
To help visualize an earthquake swarm the USGS has provided the following graphic.