October 17th, 2008

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Nineteen Years Ago

It has been 19 years since the Loma Prieta earthquake. The significance of that for me is that I was 19 years old at the time, so it essentially is a lifetime ago (or half a lifetime, depending on how you look at it).

And yet, I remember that day so well.

Recently, I looked at a geological map and realized that I was much closer to the epicenter than I had been estimating over the years. I always said that I was about 10 miles away, but in fact I was only 3 miles away, if not closer.

That explains why in Soquel/Capitola I had no warning, compared to so many of the videos you see from northern Santa Cruz or -- especially -- way up in San Francisco, where you see people "feeling it out" before realizing it's a big one, or having time to talk about it: Witness the TV announcer at the World Series starting to stumble on his words for a few seconds, then Al Michaels chimes in, "I tell you what: We're having an earth--" before the power goes out.

Watching an animated shakemap bears this out, too. Where I was pretty much is instantly in the "red zone" of severity, while these other places built up to it.

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Turns out, of course, that this was not "The Big One", but just "The Pretty Big One". We were told that, within 20 years, the Hayward Fault would produce the next "Big One". That was 19 years ago. Indeed, an article in today's Santa Cruz Sentinel quotes a geologist as saying that such faults typically produce a major earthquake every 140 years, and Hayward's last was in 1868.

That's way up north near San Francisco though, so we're likely to be as lightly scathed by that as San Francisco was by Loma Prieta (never mind the videos often seen of the S.F. area's outdated highway collapse and the Marina district which was built on landfill -- ironically from 1906 earthquake debris -- as those were fully expected to fall apart, but the majority of S.F. was unscathed, unlike Santa Cruz where more than half the buildings downtown were destroyed or damaged beyond repair and soon demolished).

But those of you in S.F. (chocorisu and toonygal!) had better have an earthquake survival kit. S.F.'s old underground water system will break just as it did in both 1906 and 1989, leaving no water to drink nor to fight fires, and there are fewer fire-fighting pump boats today. When the next Big One hits the S.F. area, S.F. will fare worse than Santa Cruz did in 1989. Most of the city is built on loose, dangerous man-made land; it is geologically wetlands, with only a few blocks actually built on bedrock. It will be worse this time than in 1906, because ferries and trains are no longer the primary means of transport, and the roads will be impassable by car, so the only viable way out to escape the fires will be on foot.

So, those in S.F., when the Big One happens, don't hang about afterward. Get hoofin' south (unless by some miracle the Golden Gate Bridge is passable). Avoid the masonry buildings (although building codes were put in place immediately after the 1906 quake, contractors complained so much about the high cost of building that eventually those codes were rescinded, thus most structures in the city were built the same way as the ones that had fallen apart); if the main quake doesn't send them collapsing into the street, the aftershocks will.