San Francisco earthquake, 100 years later: seismic safety practices keep Southland gas delivery system in top shape

Apr 17, 2006

Media Contact:
Denise King

Southern California Gas Co.

(877) 866-2066


        LOS ANGELES, April 17, 2006 – While a century has gone by since the “Big One” hit San Francisco, most California residents agree that the question is not if, but rather when, another powerful earthquake will strike.  Being prepared for emergencies is important for all residents and businesses, but for Southern California Gas Co.  (The Gas Company), operating and maintaining the country’s largest natural gas distribution system to the highest level of safety and reliability requires continual enhancement and monitoring of its infrastructure.

        “What has made our system stronger, safer and more reliable over the years is an aggressive pipeline replacement program, technological advances and improved practices,” said Lee Stewart, senior vice president of gas operations at The Gas Company.  “The safety and reliability of our gas pipeline system is top priority.”

        Stewart said The Gas Company’s more than 48,000 miles of distribution and transmission pipelines are designed and constructed to withstand various environmental conditions and outside forces, including loads that may be experienced in a strong earthquake.

        “We have an active seismic hazard review program and, if analyses show any of our pipeline facilities to be at risk, either at fault crossings or in areas subject to significant ground movement, we mitigate the risk and, if necessary, replace the pipeline facility to ensure the highest level of public safety and reliability,” Stewart said.

        He added that when constructing new pipelines, “we avoid installing across active earthquake faults or other potentially hazardous areas where possible and if unavoidable, apply the latest in engineering advances in the design and construction of these facilities, including the use of special materials.“

        Although the Southland’s natural gas pipeline system suffered relatively minor damage in the 1994 Northridge earthquake and almost no damage in the more recent Paso Robles quake in December 2003, The Gas Company continues to proactively address seismic hazards to its infrastructure to ensure safety and least impact to its customers in the event of a major quake.   In addition to systematically replacing older, more vulnerable pipelines, The Gas Company has continued to retrofit its aboveground facilities that are essential to its operation. 

        The Gas Company monitors pressures and flows throughout the major pipeline system 24 hours a day, 365 days a year.  In the event natural gas supply is lost in an area, the company typically has the capability to redirect natural gas to the area of impact.  This flexibility means that there is a relatively low chance for customers to lose their gas supply.
One of the key factors in a successful response to a major earthquake or other natural disaster is planning and training.

        The Gas Company holds annual emergency exercises and response training to enable quick and effective restoration of service while protecting public and employee safety.  Mutual assistance agreements with pipeline companies and neighboring utilities also aid in the quick restoration of natural gas service to customers.

        The Gas Company is the nation’s largest natural gas distribution utility, providing safe and reliable energy to 19.8 million consumers through 5.6 million meters.  The company’s service territory encompasses approximately 20,000 square miles in most of central and Southern California.  The Gas Company strives to provide exceptional customer service to enhance the quality of life in the community.  The Gas Company is a regulated subsidiary of Sempra Energy (NYSE: SRE).  Sempra Energy, based in San Diego, is a Fortune 500 energy services holding company.  To learn more, go to