An earthquake last March near the Brazeau Reservoir, a large dam in east central Alberta, has prompted the province’s energy regulator to restrict oilfield fracking in the surrounding area.

The Alberta Energy Regulator “says hydraulic fracturing operations targeting the Duvernay underground formation or deeper are prohibited within five kilometres of the Brazeau dam infrastructure,” The Canadian Press reports. “Hydraulic fracturing or fracking—where water, sand, and chemicals are injected under high pressure to break up tight rock and free trapped oil and gas—is also banned for shallower operations within three kilometres.”

AER rules require fracking companies to report any “seismic event” above 1.0 magnitude, and suspend operations if they detect a quake at 2.5 magnitude or higher, CP states. The epicentre of the March quake was about 75 kilometres south of the dam, and it was not immediately linked to fracking in the area.

“Earthquakes induced by hydraulic fracturing have not been observed or reported near the Brazeau dam,” the regulator said on its website. “While there is no immediate risk to public safety or the environment, we have developed these requirements as a precaution to limit the potential for an induced earthquake to happen near the Brazeau dam.”