The U.S. Pipeline and Hazardous Materials Safety Administration warned natural gas pipeline operators to be vigilant for potential damage due to earth movement amid a recent increase in pipeline ruptures and other incidents.

The federal pipeline safety regulator, or PHMSA, issued an advisory bulletin in early May reminding pipeline operators, particularly those with facilities in steep and rugged terrain, that conditions such as land movement, flooding and river channel migration "can pose a threat to the integrity of a pipeline if those threats are not mitigated."

PHMSA recommended that operators identify areas prone to subsidence, soil settlement, erosion or earthquakes; identify soil strength characteristics, ground and surface water conditions and other factors affecting system integrity, with the help of geotechnical engineers; and develop mitigation measures and construction and monitoring plans based on site-specific hazards, if any.

In the case of any damage or shut-in due to geologic hazards, the operator is tasked to inform PHMSA or state pipeline safety authorities before returning the pipeline to service or increasing its operating pressure. The operator may be required to implement additional safety measures after reporting any such incident.

PHMSA noted a number of accidents and safety-related incidents in the U.S. in the last three years caused by geological events, the most recent of which was a pipeline rupture in Harrison County, W.Va., on Jan. 29. The rupture was caused by a nearby landslide that moved the pipeline about 10 feet from its original location.