Hydraulic fracturing (fracking) on Friday was suspended for at least 30 days in a sensitive corner of the Montney natural gas formation in northeastern British Columbia (BC) while an investigation is completed into two earthquakes that struck on Nov. 29.

The BC Oil and Gas Commission (BCOGC), in announcing the safety precaution, said an initial inquiry showed the source of the magnitude 3.4- 4.5 tremors was in the Septimus field, a Montney drilling zone southeast of Fort St. John. No damage or injuries were reported, but shaking was felt on the land surface.

The BCOGC did not blame the shocks on fracking or speculate on any other possible cause, and it said more time is needed to complete the investigation.

However, an agency bulletin noted that Canadian Natural Resources Ltd. (CNRL) was operating in Septimus at the time of the earthquake. CNRL immediately halted some work and may only resume with BCOGC consent.

All other companies with Septimus drilling rights also committed to postponing activity for at least 30 days and will only be allowed to proceed after informing the regulatory agency.

The investigation and activity suspension follow BCOGC safety directives resulting from technical studies since 2012 into suspected links between earthquakes and unconventional drilling. Precautions also include a network of 20 seismic monitoring stations.

In a tremor-prone unconventional gas region called the Kiskatinaw Seismic Monitoring and

Mitigation Area, the BCOGC directives require field operations to stop immediately if shocks greater than magnitude 3.0 occur.

The BC drilling safety regime was developed with Canadian industry cooperation. The Alberta Energy Regulator also enforces precautions against drilling practices liable to induce earthquakes in its share of unconventional gas and oil formations.