LUFKIN, TX (KTRE) - Two new studies from groups in Texas and Oklahoma have linked oil filed drilling operations to the recent increase in Earthquakes.
In an Associated Press report, the Oklahoma Geological Society says it is "very likely" that most of the state's recent earthquakes have been triggered by the subsurface injection of wastewater from oil and natural gas drilling operations.
The society investigated dozens of earthquakes in central and north-central Oklahoma. It said Tuesday that, based on seismicity rates and geographical trends following major oil and gas operations that produce a lot of wastewater, the rates of earthquakes are "are very unlikely" to be the result of a naturally occurring process.
The society said the "primary suspected source" is not hydraulic fracturing, or fracking, but wastewater injections.
Geologists historically recorded an average of 1.5 earthquakes of magnitude 3 or greater each year. The state is now recording an average of 2.5 magnitude 3 or greater earthquakes each day.
Scientist at Southern Methodist University also released data for the North Texas area.
A study published Tuesday in the journal Nature Communications says researchers from Southern Methodist University and the U.S. Geological Survey monitored the shaking from nearly 30 small quakes around Azle from November 2013 to January 2014. The area hadn't had any recorded quakes in 150 years.
The scientists say the shaking decreased when the volume of injections did. They have concluded that removing saltwater from the wells and injecting that wastewater back underground is "the most likely cause" for the swarm of quakes.
Other studies have made a connection between wastewater injections and a spike in earthquakes in Oklahoma and southern Kansas.