Matt Springer has been giving presentations around San Francisco about home earthquake preparedness since 2008 (for more information about the presentation, go to his earthquake preparedness website). This Quaketips blog is devoted to posts ranging from technical "how-to" articles to more philosophical "should-you" topics. New articles will be posted at most about once a month, so people who subscribe won't be subjected to lots of e-mail.

Sunday, August 24, 2014

Reflections on the San Francisco Bay Area’s largest earthquake since 1989

I only post articles here about once a month or less, but I’m posting just a few days after my previous article because the San Francisco Bay Area got woken up last night by a moderately strong earthquake, magnitude 6.0.  This is the largest quake to hit this region since the 1989 Loma Prieta earthquake, and the first since then to result in substantial damage to buildings and infrastructure (in Napa and Vallejo, north of the San Francisco Bay).  I don’t have any information about this earthquake that people aren’t already getting from the news, so I haven’t attempted to rush to post something.  Instead, having followed the news out of Napa during the day, a few thoughts have come to mind.

First, ironically, I had just given one of my talks earlier that afternoon, in the library in my own neighborhood.  I’ll bet the people who attended are marveling at my ability to deliver real live examples of my subject matter!

I do have a couple of more substantial observations though.  Nobody wants to experience structural damage and injuries at any level, but these moderately large quakes provide a good reminder of what can occur, if viewed through the appropriate lens.  Some of you may have read my article from 2011 about benefits and dangers of small earthquakes to our preparation for large earthquakes.  The bottom line was that when people who have never experienced a strong earthquake feel some small earthquakes, they might vastly underestimate the potential risks of the larger ones and not feel the urgency to prepare.  This Napa quake, at a 6.0, was roughly 10-fold smaller than the 6.9 Loma Prieta quake that caused substantial damage, injury, and mortality.  The residents in the hardest hit portions of Napa have a very good concept now of what may happen in an even larger quake, but for many of us in San Francisco and the rest of the Bay Area, our experience with a 6.0 quake was a rolling in the middle of the night, followed by going back to sleep.  Don’t limit your personal experience with 6.0 earthquakes to what you personally experienced; base it on what they experienced in Napa.

It is also notable that the photos and personal accounts from Napa are consistent with what you have been hearing all along from me and from emergency preparedness organizations: don’t attempt to run out of the building during an earthquake, and get UNDER something stable, not next to it.  The piles of bricks and other rubble directly next to buildings are what you could encounter if you were exiting the building, and the rubble also should remind us of the fallacy of seeking safety next to a sturdy object rather than under it.  Napa residents interviewed by the news described being hit by objects from the wall, and said that everything that could fall did fall; and there were lots of photos from inside people’s homes showing many objects that fell off of shelves or out of kitchen cabinets that swung open.  In fact, much of this interior damage could have been prevented by appropriate bracing, quake-resistant cabinet latches, sticking objects to surfaces with quake putty, etc.

That is, at the risk of hitting you over the head with it, you can greatly reduce the probability of many of the problems encountered in Napa by taking the recommended home preparedness precautions against earthquakes beforehand!

So, I hope that the worst is over for Napa and that they don’t experience strong enough aftershocks to cause more problems.  Nonetheless, we should derive as much benefit as we can from these occasional 6’s by imagining what we might experience in the 7’s and 8’s, and then taking the appropriate precautions now.

As for me, believe it or not, I slept through most of it.  Because I think about earthquakes frequently as I give my talks or write this blog, I occasionally wake up from an earthquake dream that simply consists of the whole room shaking, some of which are darned scary.  For the real thing, by the time I realized something was really going on, it was almost over.  I’m disappointed!

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