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Consider quakes in construction questions

Ken Norwood Berkeley
Friday January 04, 2002


The recent story regarding the use of flexible gas pipe in building construction overlooked a related and critical earth quake safety issue. Gas meters have traditionally been connected to houses and other buildings with conventional ridged steel pipe and inflexible connecting elbows, couplers, etc. This ridged steel pipe system connecting the gas meter can crack or snap under earth quake forces, as has been shown recently in the Loma Preita and North Ridge shakers. By far the greater danger than ground shaking is that of fire storms. 

Many damaged houses can be repaired, but once fires start entire blocks, for miles, will be destroyed by fire (remember 1906), especially because of ruptured water mains. 

The older urban Bay Area communities are more vulnerable to fire storms than in any California earthquake zone due to the number and age of wood frame houses built since the 1906 quake and up to W.W. II. This is especially serious in the East Bay from Albany throughout Oakland, and south to Fremont, as well as older San Francisco neighborhoods. The specific hazard is that there are a large number of pre-W.W. II one and two-story wooden houses sitting up on short pony walls, usually made of 2x4 studs and wood siding. These unreinforced lower areas are very vulnerable to shifting and tilting, thus putting stress on the gas pipe and joints between the gas meter and the house wall. This failure will be one of the major sources for fires after a quake, the other being unstrapped water heaters and other gas appliances. The ridged gas pipes within walls area also vulnerable to cracking, and here again flexible gas pipes could be a valuable safeguard when shifting of the building occurs. It would take only a few inches of movement to snap old and probably rusty gas pipe connections. 

Sounds obvious does it not? Then why does Pacific Gas & Electric, emergency services departments, and building departments balk at instituting a region wide program to make this very inexpensive flexible connections at the gas meter.? (Water heater earth quake strapping and flexible gas pipe are already required, as are flexible pipe connections to kitchen ranges.) 

It appears that PG&E is the major stumbling block – the meters are theirs. And, why is there acquiescence by earthquake engineers and emergency agencies? Maybe this trail runs through the entire political spectrum and involves the real estate, lending, commercial property owners, and developer interests. Some one is benefiting from the above inaction. 

Perhaps there is a city council member, state legislator, or a U.S. Congress person who will investigate the above allegations and how state and federal funds for earthquake preparedness are being spent. 

Lastly, who are the emergency preparedness officials at local and upper levels who have not called our attention to the likelihood for fire storms (remember 06) in old wood frame neighborhoods. Please do not feel safe because you have already retrofitted your foundation walls, if there area any houses in your block not reinforced and without flexible gas pipe connections you are vulnerable.  


Ken Norwood