Turns out, what you don't know can
hurt you. It can even kill you. We don't give much thought to the network of aging PG&E piplelines running beneath our feet,and powering the flames beneath our pots and pans. But a ruptured pipeline leading to the immolation of a 10-acre swath of San Bruno
suddenly cast those subterranean pipes in a new light. If a postwar-era vessel can up and explode just like that, will the inevitable next great Northern California earthquake lead to scores of San Brunos, whole towns and cities erupting into Dresden-like infernos, and a reduction of our region into twisted wreckage?
Hopefully not, says one expert.
is an associate research seismologist at U.C. Berkeley. When asked what new information the San Bruno disaster imparted to her about the dangers of living above aging gas pipelines in earthquake country, she immediately replied "nothing, really."
That there are many pipelines in the ground and that they occasionally explode is not news to Hellweg. She points to a 2004 blast that killed five workers
after a backhoe pierced a pipe in Walnut Creek. But massive conflagrations that'd put San Bruno to shame may not be the death of us all. The scientist points out that ruptures in one section of a pipeline ought to trigger a shutdown in other sections. That means, "unlike the Deepwater Horizon
," the "endless resources of PG&E" should not keep flowing through a flaming, ruptured pipe, fueling a massive fire. (That being said, PG&E does not have automatic valves to stem the flow of gas on all of its pipes -- and it took workers nearly two hours to manually shut the pipeline down
during the San Bruno fire).
Automatic valve shutoffs or not, Hellweg points out that Northridge did not go up in smoke during its massive 1994 quake
. Yes, water mains and gas mains broke, so "you had a beautiful gas fire shooting out of the water mains." But, she adds, "there wasn't a ubiquitous breakage of gas lines everywhere."
Finally, while San Francisco burned following the 1906 earthquake, Hellweg is optimistic things won't play out in exactly the same way the next time. First off, city firefighters were hopelessly handicapped in '06 when fire chief Dennis T. Sullivan was killed in the quake. These days, disaster response is ostensibly more organized, and is also better spread through multiple layers of command.
It was improper response to the encroaching flames -- including clumsy use of dynamite -- that led to much of San Francisco burning, Hellweg says. We've gotten better at fighting fires in the last 104 years, she notes. But, she acknowledges, we also have far more subterranean pipes that may rupture. And some weren't installed so long after '06.
In fact, water and sewage pipes -- also well past their declining years -- stand to rupture in the forthcoming quake. That won't kill you in a ball of flames, but it can present massive problems for a city hoping to put out fires or avoid a dysentery outbreak.
Yes, it turns out that what you don't know can kill you. But it may not kill you in the way that you thought.
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