Geophysicists and state regulators say there’s no induced seismicity from the state’s oil extraction.
The major temblors that rocked Southern California July 4 and 5 were the state’s biggest in 20 years and powerful reminders that the Golden State is indeed earthquake country.
Although they’re rarely felt by humans, thousands of earthquakes occur naturally here every year. National Geographic recently reported that every three minutes, an earthquake strikes in California.
But none of California’s temblors has been linked to oil production, say geophysicists and state regulators.
Responding to a question at a July 7 news conference, Dr. Egill Hauksson, a seismologist with the California Institute of Technology, told reporters that Kern County “fracking” had nothing to do with the earthquakes.
Hauksson’s answer corroborates what other scientists and studies have reported in recent years. The California Council on Science and Technology studied well stimulation in California and reported there is no evidence linking hydraulic fracturing or produced water disposal to “induced seismicity,” or earthquakes caused by human activity.
John Parrish served as the state geologist from 2005-18 with the California Department of Conservation. “The process of hydraulic fracturing does not pose a high risk for inducing felt seismic events,” noted Parrish, who also chaired the California Earthquake Prediction Evaluation Council.
Dave Quast, California director for Energy In Depth, reported in 2015 that “of the approximately 42,000 Class II underground injection wells in California, not one has been linked to seismic activity.”
That hasn’t been the case in other parts of the country. Disposal into deep injection wells of water produced from oil and gas operations has caused felt seismic events in several states, Quast said.
California’s unique differences
What makes California different are, in part, its modern methods of extracting oil and gas.
“Producing in a fault-laden region means adopting best practices to ensure that seismicity does not become an issue,” Quast said.
California oil and gas companies are subject to the nation’s toughest regulations to ensure the safety of communities, the environment and employees, said Gary Myers, Aera geophysicist. Those regulations include tough permitting rules, unprecedented disclosure requirements and extensive monitoring and testing.
“Produced water is typically disposed of into soft, or less brittle, rocks or in previously produced zones that are now depleted and under-pressured, thus greatly reducing the risk of inducing seismicity,” Myers added.
In addition, California’s geology is quite different from that of the midcontinent and eastern states, where the productive formations – rock formations that produce oil and gas — tend to be quite a bit older and far more consolidated. “In California, in general, the productive formations are less consolidated and much younger,” said Myers.