Engineering - PDI

Shake, Bake, and Thank Goodness, our buildings Hang Tough in the Napa 6.0 Quake

By Mark Rice, Esq.

At 3:20 am on August 24, 2014, I was awoke that seemed at first a hurricane of wind blowing open my backyard door. When the loud sounds continued, like storm troopers in the house, I thought I was under siege. As the initial sounds of wind gave way to 30 seconds of shaking, rumbling and creaking, I finally realized what it was – the biggest San Francisco Bay Area earthquake since Loma Prieta in 1989. 6.0 the news said, almost instantly; then upgraded to 6.1 on the Richter scale, with its epicenter in Napa, in an offshoot of the Hayward fault – the same one that runs right through Memorial Stadium at UC Berkeley, recently retrofit and redone, where I saw the Cal Bears lose many a game, but not without hope for another return to the Rose Bowl (that is 1959 the last time for those who are counting).

Due in large part if not entirely to the evolved and committed state of seismic engineering in my state, I could go safely back to sleep knowing that in all likelihood, infrastructure would largely be intact, buildings would survive, and injuries fear, and death from earthquake improbable. Not so elsewhere in the world, where an earthquake is a sure killer, as buildings pancake, roads split like craters, and power lines electrocute.

It’s no mystery – good building codes and enforcement in a seismically active region make a difference; the April 2014 Earthquake in Chile, 8.2 on the scale, had only 6 deaths even after a tsunami, attributed to its adopting a seismically focused building code approach similar to California. As reported by CNN,

“They’re a seismically active region of the world and they are very good at implementing their building codes similar to California,” John Bellini, a Denver-based geophysicist at the U.S. Geological Survey told

CNN on Wednesday. He added, “Because of that, you would see less damage than in other places that have poorer building codes …. that’s probably one of the reasons there haven’t been as many casualties as there could have been from a magnitude earthquake of this size.”

The 2013 Earthquake in Pakistan (Mw 7.7) killed at least 825 people; the Mw 7.1 quake in the Philippines also last year, over 161 lost; the April 2013 Sichuan quake in China, over 186 deaths.

The engineers and contractors responsible for the lack of any deaths for the Napa seismic event deserve praise, as do the public servants and budget committees that kept to the commitment to a safe set of seismic building criteria and redundancies for new construction and retrofits. I saw the photographs of the major damage, right downtown Napa, the old historic courthouse (my favorite), and unreinforced masonry brick façade across the street, now a wine bar but for many years before Napa’s renaissance as a hip hub, left unattended by a 100 years of new construction techniques.

So a big thank you. I was able to go back to sleep, safe; but critically, Napa and the state was up and running right away, the damage to wine casks noted, but overall, a huge sigh of relief thanks to the fail safe design and public emergency response built into our thinking. And the Pile driving industry has been central to those upgrades that made us safe.

Now, in driven piling, seismic engineering can be frustrating to contractors, where end bearing has been reached, but a nervous engineer insists on overdriving to obtain more depth and skin friction to overcome uplift, the scenario where piling and building are shoved upward by a seismic event. In the years since the 1989 quake claims of overdriving are more common in my view. Often, more but shorter or even thinner piles would have worked better to ensure skin friction while gaining end bearing and traditional refusal measured by blow counts per foot.

Lately I have been reading quite a bit about seismic design, redundancy, critical infrastructure, and the failure modalities that occur immediately and long term when pile, foundation, or even pipes are displaced, bent or at risk of cracking and leaking. It’s more than voodoo; it’s an ongoing study of each new seismic event, like tornado chasers, engineers travel worldwide to study the exact oscillation of the most recent quake to learn its lessons for design. As engineers know, it matters which direction the fault is compared to your building or pipe (parallel, perpendicular across, lateral), and the type of quake encountered. It’s a call to action, not just in the US and in seismic arena’s, but worldwide, where our best and brightest engineers and seismic experts can accomplish for others, what they have done here – make us safe.

Graphic Designer and film creator Saul Bass is quoted, “design is thinking made visible.” True, but design is also life made survivable. Einstein once said, “All Science is the extension of ordinary thinking.” True, but how far have we extended that thinking? The pile design, fabrication and construction sectors are key to updating the world’s infrastructure. Does America export anymore, at least, beyond I phones, music and good movies? We do – You do. Bravo to those that push this ball up the hill, until all seismic events have the same news story the next morning – no deaths reported. It’s possible, as here we have made it happen.