Stanford Study Finds Efforts to Reduce Oklahoma Seismicity Are Proving Effective
Friday December 2, 2016
On the same day the Associated Press reported the rate of earthquakes in Oklahoma has dropped “dramatically” since May, a new study shows how current wastewater injection policies could reduce Oklahoma’s seismic activity to background levels in five to 10 years.
The new report, co-authored by Stanford University geophysicist Mark Zoback and colleague Cornelius Langenbruch, used a physics-based statistical model in Oklahoma’s two most seismically active regions to find,
“On the basis of our results, the mandated saltwater injection rate reduction in 2016 was an effective step in mitigating the seismic hazard associated with the occurrence of triggered and induced earthquakes in Oklahoma because injection rates in both CO (central Oklahoma) and WO (western Oklahoma) drop below the observed triggering thresholds. Consequently, widely felt M ≥ 3 earthquakes in the affected areas, as well as the probability of potentially damaging events, should significantly decrease by the end of 2016 and return to tectonic levels within the next few years.”
In February and March of this year, the Oklahoma Corporation Commission (OCC) issued directives to reduce wastewater injection into the Arbuckle formation by 40 percent below 2014 levels in the state’s two most seismically-prone areas — central as western Oklahoma. The Stanford study suggests those policies — along with the market downturn — are effectively reducing the number of earthquakes in the state.
Previous research from EID showed that the rate of earthquakes in Oklahoma of magnitude 2.8 or greater had declined 81 percent in November when compared to the peak month of June 2015. Instances of M 2.8-and-greater earthquakes —the minimum size for which the Oklahoma Geological Survey (OGS) has a complete catalog — have also declined 80 percent from January, as the following EID chart illustrates.
