Oklahoma may expand earthquake prevention plan: UpdateOREANDA-NEWS. July 15, 2016. Oklahoma regulators are investigating oil and gas operations near Blanchard, Oklahoma, searching for any ties to a recent uptick in earthquake activity.

The area in focus is outside of the 15,000-square-mile region where wastewater disposal well activities have been restricted to prevent earthquakes. The investigation could lead to limits on drilling or other regulations.

"We are not ruling out anything," said spokesman of the Oklahoma Corporation Commission Matt Skinner.

The area near Blanchard has seen nine earthquakes in the past seven days, according to the US Geological Survey. The largest has been a 3.4 magnitude earthquake. The area has not seen as much seismic activity as a region in northern Oklahoma up to the Kansas border.

The state overall has seen a large increase in seismic activity in recent years. Many of the recent earthquakes have been in regions with wells used to dispose drilling wastewater into the Arbuckle formation in central and western Oklahoma. This has prompted the state to implement an earthquake prevention plan in those regions which includes limits on more than 600 wastewater disposal wells.

There are no deep Arbuckle disposal wells within at least 20 miles of the recent earthquakes near Blanchard.

The sharp increase in earthquakes in Oklahoma has coincided with a surge in oil and gas drilling activity. The number of earthquakes in Oklahoma above a magnitude 3.0 increased to more than 900 in 2015, compared to about 580 in 2014 and about 100 in 2013.

Earthquakes near Cushing, Oklahoma, have been of special concern because it is a major crude storage hub, with about 64mn bl of oil stored there currently, according to the US Energy Information Administration.

The Oklahoma Corporation Commission does not have an estimate on how much oil and gas output has been curtailed because of the earthquake-prevention regulations.