The number of “felt” Oklahoma earthquakes — those registering magnitude-2.8 or greater on the Richter scale — fell 58 percent in 2017 from 2016 levels, according to an Energy In Depth review of United States Geological Survey data.
The monthly average number of M-2.8 and greater earthquakes in 2017 was also down 82 percent from the June 2015 peak, and felt earthquakes were down 71 percent from levels seen in Oklahoma’s most seismically active year of 2015.
The number of manmade, or “induced,” earthquakes in Oklahoma had risen dramatically since 2009, due largely to wastewater amassed during oil and gas recovery operations being injected deep underground into seismically active areas.
But an 18 month old regulatory initiative from the Oklahoma Corporation Commission has effectively turned the tide and gradually calmed down a seismic phenomena.
Clusters of earthquakes in Oklahoma have been linked to wastewater injection from oil and gas drilling. The photo shows the massive increase in returned saltwater, into disposal wells, along with the correlating quake activity.
But new state regulations that call for reductions in wastewater injection has significantly decreased the rate of induced earthquakes in Oklahoma in the coming years, Stanford scientists say in an article in Science.
Over the past 5 years, Oklahoma tried a number of measures aimed at reducing the rising number of induced quakes in the state, but none of those actions were effective.
While wastewater produced during oil and gas drilling has been disposed of by underground injection in this area for many decades, induced seismicity was not a problem until the volumes being injected were massively increased, beginning around 2009. In the past 8 years, billions of barrels of wastewater were injected into the Arbuckle formation, a highly permeable rock unit sitting directly atop billion-year-old rocks containing numerous faults.
The Famous 'Labor Day' Quake
On Saturday morning of the 2016 Labor Day weekend, there was Oklahoma's largest quake on record. At around 7am, I was awakened by a violent swaying of my 2nd story bedroom. Our teenage daughter was frantic as she joined my wife and me in the upstairs hallway, hugging the door frames for several seconds.
When calm restored, I went to my office and pointed my laptop browser to the USGS website. Within about 15 minutes the US Geological Service had the initial report and a GPS coordinate. I plugged that data into my Google Earth software and I was immediately taken to a petroleum facility in Pawnee County, about 60 miles from my home.
I reported my findings to this news service and published the information to the web even as aftershocks continued to rock my Tulsa, OK home.
Over the next week my report went viral and news services around the globe carried my screenshot of the oil field with the 'pin drop' of the epicenter in the field behind the storage tanks.
The Oklahoma Corporation Commission has been loudly criticized for dragging their feet while they tried minimalist tactics to stop the quakes. In 2014 the first efforts were quietly mandated. Those measures had measurable but limited success. After the 5.8 quake of Sept 2017, the OCC finally took real and effective measures.
To that point, the Oklahoma Corporation Commission had stayed behind the walls of their office, next to the State Capitol building, in Oklahoma City. Their only communication with the outside world during the previous few years was by emailed press releases.
I publicly demanded real response and a press conference, so that the questions of reporters, victims, and local governments could be expressed.
By Tuesday, the Oklahoma Corporation Commission had responded. They set up a public symposium at The University of Tulsa to be held by midweek. They notified the EPA of their game plan and the federal govt. The Obama Administration decided to lend executive branch federal support and assure the state of Tribal cooperation, especially in Osage County (just a few miles from the latest epicenter.
We're about 70 days into 2018. there are 54 recorded quakes of 2.8, in the Oklahoma zone. That's about 1.22 noticeable quakes per day. What Oklahoma Oil producers need is a safe way to inject their waste saltwater back into the depths of the earth without harming our ecosystem or our fault lines. We used to have about 1.6 noticeable quakes per year. It may be a long time before we get back to that level of geological boredom.