30 July 2008

A Little Rattler in the Canyon (no, not a snake! a quake!)

All right, all right, so it was a minor quake, a mere 5.4 that was only a fraction as powerful as the Northridge quake of 1994. I guess that, because it had been almost 15 years, many had forgotten what these things were like. I also suspect that the advent of 24-hour media, with all that time to fill, makes these events look far worse, especially to nervous family and friends out of state who only deal with tornadoes, hurricanes, floods and other natural calamities where they live.
Yet, here Chino Hills was having its fifteen minutes of fame for being the epicenter of a little rattler that broke a few windows, spilled some canned goods, knocked grandma's porcelain ballerina figurine down off the curio cabinet, and shook more than a few nerves. I imagine we all thought the big faults were Andreas, or Whittier-Fullerton, or some other that would be far from us.
The fact is: damage from earthquakes can be most severe at places somewhat far removed from the epicenter and dependent on the movement of the quake, the geologic conditions (soil and other factors), and the quality of the construction in any given area.
I'm not trying to minimize the reaction some people had: 5.4 is a fair-sized, if moderate, tremor.
But, folks, the "Big One" that the seismologists warn us about, the one that has a 90% chance of probability in the not-too-distant future (10 years? 30 years?) is going to be 8.0 or greater, meaning close to 30x more powerful in amplitude and 100x greater relative to the release of energy than this relatively harmless event we experienced today.
Would this "Big One" occur on a fault running through Chino Hills? Evidently not, since the Andreas Fault is most likely the one from which a "great earthquake" of over 8.0 magnitude would come. But, anywhere within a wide-ranging area would be significantly affected, so we can assume canyon folk would be as impacted as millions throughout our massive, sprawling region.

And, just when was the last "Big One" in the Los Angeles area? 1857. So, I guess we're due.
Stock up that earthquake kit, have plans for escape and a gathering place established, and, whatever you do, don't start bolting for the nearest exit thinking that outside is the best place to be during a quake.

I still can't fathom people doing that, knowing that exterior building surfaces, entire walls, power lines, trees, and other objects are more likely to kill people in this region than anything inside. The horrific scenes from China earlier this year of totally collapsed buildings, with pancaked floors crushing thousands, is as much a reflection of shoddy construction and a lack of strong earthquake mitigation codes as anything else and is unlikely to be repeated here in the same way. Unfortunately, those scenes might convince some people here to hightail it for outside despite the obvious differences between Sichuan and Los Angeles.
This isn't to say that a comparable quake of 8.0 here won't cause building collapses. But, the only instance where leaving a building is recommended is when you are in an unreinforced adobe building. I happen to work at a place that has one of those (and there was an archaeologist inside studying the building when it happened--guess where he went?) but for the 99.984% (approximately) of us who aren't in one when the quake hits, stay inside, take cover under sturdy furniture or against a wall (and away from glass and other potentially damaging objects) and ride the sucker out. And, be prepared for powerful aftershocks that could cause great damage in weakened structures.
Canyon folk: I suppose that in a "great quake" event, we could see landslides and cracking closing down Carbon Canyon Road, some hillside homes slipping, and other major damage. Being three miles or so from just about anything, with power lines above ground, and what have you, it would appear to be an imperative to have plenty of emergency rations around the house. I didn't get something like this together until a few years ago and am not sure if I'm entirely prepared if my house is unsafe to reenter. But, I do have a 48-hour kit outside in a sealed plastic container (the kit even has a toilet seat that fits over the container--just in case!) and there are 48-hour backpack kits in the two cars. So, maybe that will be sufficient, though many experts suggest more.
At any rate, our little rattler next to Carbon Canyon ought to be a reminder about what we potentially face in our region and preparedness is probably about as shaky (oops, sorry) as our savings-to-debt ratio.

With all of the emphasis on fire safety (definitely needed), we shouldn't forget about this other potential canyon calamity. Today sure brought that home for me.

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