Late Night Musings of an Earthquake Seismologist

by Paul A. Reasenberg

Originally published in the Perspective Section, San Jose Mercury News, January 23, 1994 (one week after the Northridge, CA, earthquake).

What does an earthquake scientist think about late at night? Have I gleaned any useful insights from my dual roles as a researcher of faults and earthquakes in California and as a home owner living near the San Andreas fault in a very old house in Palo Alto, California? How do I feel about earthquake risk, and about risk in general, knowing what I know? Is my experience of living in earthquake country similar to or different from yours?


This past week, you have probably thought more about earthquakes than you have in the last 4 years, since 5:04 PM on October 17, 1989, when the Loma Prieta earthquake rocked the Bay Area and, like a slap across the face, seized your attention. Maybe your fears, palpable then, have been reactivated now, and you have vowed, finally, to do something to protect your house and family. More likely, I would guess, you had a good scare in 1989 but did not sustain any damage or injuries at all. Oh, maybe you were inconvenienced a bit on the freeways, but admit it: the TV coverage was riveting -- better than any TV mini-series in recent times, and in some ways you actually may have enjoyed being a "survivor" and being talked about by the whole country and written about in magazines. Perfectly natural. I used to love hurricanes and blizzards when I was a kid growing up on the east coast. The excitement and awesome display of nature's power can be exhilirating and can make an otherwise boring week into a pretty memorable time.


I remember seeing my neighbors after the Loma Prieta earthquake. Our homes were damaged only very slightly by the earthquake, although some chimneys did fall in our neighborhood. We all talked together out on the sidewalk, comparing notes on what fell down and about how we got home through the traffic chaos, how we lit candles during the power outage and how our we, our kids and pets coped. There was an increased sense of community. We felt like survivors, and that felt good.

On the other hand, many people did suffer tragic or serious losses in Santa Cruz, Watsonville and the Bay Area in 1989, and in Los Angeles last week, and many others were downright terrified by those earthquakes. For them, an earthquake is obviously an intensely horrible thing. However, since 1906, the vast majority of the Bay area's population has not been hurt in an earthquake. In apparent contradiction to the warnings we receive, the fact is that, for most of us, our accumulated experience of earthquakes is not negative, and for some, it may even be positive. And even if we were really scared in 1989, our fears have probably subsided somewhat. Its natural; we drive really slowly after we experience or witness a traffic accident, but may lapse back to driving faster soon after.

To be fair, I admit that I have more to like about earthquakes than most people have. This is because, after a large earthquake, in my role as earthquake maven, I am invited to go on TV news and radio programs to share information and answer questions, I am quoted in the newspapers, and later give scientific talks and write papers for scientific journals. A large earthquake in California produces a wealth of new data demanding analysis. It also produces a rush of professional and public activity for me, and I am exhilerated by it. I imagine that firefighters, doctors and legislators share these feelings; most of the time our work is routine and anonymous, but occasionally we get to do something really dramatic and appreciated by others.


So, here we are again: an earthquake has just happened, we all watched it on TV, and we're all talking about it. But what will you do about it? The answer probably depends on how you tend to approach risk in your life, and this can be a very personal thing. I, for one, tend to be very risk-averse. I've always chosen the high-option coverages in my auto insurance, and I have earthquake insurance on my house. I wear a bike helmet. As a parent, I tend to be very cautious, as my kids will attest. I prefer low-risk, low-paying investments. Others may like to gamble, investing in high-risk, high-return offerings, while going light on insurance and safety measures such as buying some fire extinguishers for around the house. Sociologists know that gamblers often are willing to risk large sums of money for a potentially large, future gains, but tend not to be willing to spend even a small amount of money to avoid an equally large potential loss.


The gambler might say to me that I have been a loser so far, because I've spent a small fortune on earthquake insurance premiums (about $5000 in the 18 years that I've owned my house) and I haven't collected a cent in payouts yet (knock on wood!). He'd be right, given his values. And with the 10% deductible in the policy, I may never get anything back (unless there's big earthquake damage). From my perspective, that's OK, because my house is my nestegg, and I value the protection of my nestegg more than the prospect of increasing it slightly. What you do in your situation will reflect your own values.

I also bit the bullet and paid about $1500 to have my house retrofited. It's an old, wood-frame house, built in 1906 (just after the earthquake, I suspect). It needed bolting to the foundation, and installation of some posts, beams and shear wall reinforcements. Whether or not we invest in retrofitting our homes, or, for that matter, purchasing an extended warranty for our car or appliances, reflects our feelings about risk and risk aversion. Its a gambler's choice, its a personal choice.


How we make these choices depends, to a large extent, on our experience. As much as we like to think of ourselves as rational, we often judge a situation relying more on our experience than on other kinds of knowledge. We know to not touch a hot stove because we've each been burned, at least once. We never forgot it. We know that we are living with earthquake hazard. By now, we've all heard that the odds are 2 to 1 in favor of having a magnitude 7 earthquake in the San Francisco Bay area sometime in the next 30 years. That means its twice as likely as not! All of us have been told this, and now we've also seen others hurt in earthquakes. But most of us haven't actually been hurt in, or suffered a major loss from, an earthquake. That's our experience, and experience sometimes speaks louder than words.


And I fear that those of us who did experience the Loma Prieta earthquake actually may have developed a false sense of security from it. "We had our earthquake, and we got through it, so what's the big deal?" But we didn't have our earthquake. Santa Cruz had theirs. It was 60 miles away from San Francisco, and while it released five times more energy than last week's L.A. quake, it was centered up in the Santa Cruz mountains, away from most people, buildings and bridges. It's the distance that saved most of us in the Bay area, folks. Unfortunately, I'm afraid that for many of us, the experience ("We got through it, no sweat!") is speaking louder than the seismological warnings ("The expected earthquakes in the Bay area will be more devastating"). And that's too bad. Because really big, bad earthquakes in densely populated areas don't happen often enough for everybody to learn by experience. And even for those of us persuaded by the warnings, the longer we wait after an earthquake, the more likely we tend to forget the warning. Other pressing needs come along. Who wants to think about it? Who wants to spend money to mitigate the losses from something that we've never experienced? It reminds me, sadly, of the old joke about the optimist who jumped from the top of a 20 story building. He was heard saying, as he wizzed down past the tenth floor, "So far, so good!"