Slowly but surely, seismic researchers are strengthening their conclusion that the swarm of North Texas earthquakes in recent years have been human-induced.
Texas Railroad Commission, are you listening?
Research has long established a probable link between tremors and pressure from wastewater injection disposal wells used in oil and gas operations. However, new research from an SMU-led study team, including experts from the University of Texas and the Geological Survey, adds a chilling caution.
The Johnson County town of Venus, which experienced a 4.0-magnitude earthquake in May 2015 — the strongest quake ever recorded in North Texas — sits on an unpublished fault with the potential to produce an event 10 times as large and release 32 times as much energy. The report also concludes that there’s "substantial evidence" that underground disposal of wastewater from oil and gas operations caused those tremors.
When will the Texas Railroad Commission, which regulates and promotes the oil and gas industry, accept such compelling evidence? They pushed back against this study, issuing a statement that there was "no conclusive evidence" tying the wells to the earthquake. They had also pushed back publicly against an earlier SMU-led team’s report establishing a strong link between injection wells and a swarm of tremors in Azle in 2013.
Previous reviews of natural and human-induced tremors from the U.S. Geological Survey concluded last year that this region faces a 1 to 5 percent chance of an earthquake strong enough to damage buildings in the next year. That risk is 10 times as high as it was in 2008, when earthquake swarms began shaking this region. They now number more than 200.
The fault responsible for the 2015 quake near Venus is at least 4 miles long and holds the potential to produce a 5.0-magnitude or greater earthquake if it ruptures along its full length.
However, a magnitude 5 quake is not inevitable along this fault line.
In the face of increasing risk assessments from reputable independent researchers, the Railroad Commission should heed the advice of SMU researcher Heather DeShon, who led the new study. She says that shutting down individual wells may not slow the size or rate of tremors, adding that "from a mitigation standpoint, you need to start thinking in terms of the cumulative history of injection in regions."
Tremors with a magnitude of 5 are considered moderate, enough to crack walls and ceilings, at most. Nonetheless, the Railroad Commission needs to pay attention since the Geological Survey and others say they can’t rule out the possibility that injection well activity over time will trigger something like the 5.6-magnitude quake near injection well sites in Prague, Okla., in 2011. At that magnitude, there would be substantial property damage and injuries in heavily populated North Texas.
In this era of mega-natural disasters, we don’t want to be an area that had warnings and ignored them.
Preparing for the future
"From a mitigation standpoint, you need to start thinking in terms of the cumulative history of injection in regions."
SMU researcher Heather DeShon
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