A spike of earthquake activity near the city of Blanchard has prompted state regulators to investigate oil and gas operations in the area.
At least nine quakes have been recorded near the small community southwest of the Oklahoma City metro, including 3.4 and 3.1-magnitude temblors within days of each other.
The shaking has ranged from light to moderate. The Blanchard quakes are outside a 15,000 square-mile zone established earlier this year, where regulators asked oil companies to reduce activity at disposal wells thought to be triggering the shaking.
The Corporation Commission said Wednesday it is reviewing all oil and gas operations in the Blanchard area.
