Oklahoma’s Republican Governor, Mary Fallin, wrote a December 9 letter to California Governor Jerry Brown thanking him for the help Caltrans officials have offered educating Oklahoma officials regarding earthquakes.

Fallin acknowledged the aid of Caltrans experts who have shared “their knowledge and expertise” with Oklahoma officials as “we learn more about mitigating risks associated with these ‘new to us’ natural phenomena,” according to the Sacramento Bee.

Fallin apparently mentioned a “direct correlation” between the earthquakes in her state and disposal wells from hydraulic fracturing, or “fracking.”

The Bee notes: “Many experts link the shaking to disposal wells from oil and gas drilling operations, including fracking.”

Yet as the Oklahoma Daily reported, Jeremy Boak, director of the Oklahoma Geological Survey has pointed out that the growing number of minor earthquakes in Oklahoma are likely due to naturally occurring water that is removed with oil and gas production, as only roughly 5% of the wastewater injected into the earth is fracking-flowback water.

Minor earthquakes of magnitude 3.0 or greater have increased recently in Oklahoma, from 109 in 2013, to 584 in 2014, to 850 in 2015. As a result, the Oklahoma Corporation Commission has ordered certain disposal wells to reduce their depth. Others must reduce the volume of produced water that they’re injecting.