Norman, Okla. -- The U.S. Geological Survey in conjunction with the Oklahoma Geological Survey have issued an alert for central Oklahoma.
In a joint statement, the agencies say there has been a sharp increase in earthquake activity since October of 2013. 183 earthquakes of magnitude 3.0 or greater occurred in Oklahoma from October 2013 through April of 2014.
From 1978 to 2008, the state averaged just 2 earthquakes per year. The agencies say that the likelihood of future, damaging earthquakes has increased for central and north-central Oklahoma and is the reason behind the warning.
Both the USGS and the Oklahoma Geogological Survey agree that a likely contributing factor to the sudden increase in seismic activity is wastewater disposal by injection into deep geologic formations, a process in hydraulic fracturing or "fracking."
The water is a byproduct of the fracking process and can increase underground pressures, lubricate faults and cause earthquakes – a process known as injection-induced seismicity. The agencies says the recent increase is not part of the natural seismic process.
The Oklahoma Geological Survey has increased the number of monitoring stations in response to the increased activity. The agency is now operating 15 permanent seismic monitoring stations and 17 temporary stations across the state.