Counting Seismologists or Earthquake Terminology 101

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We just had an earthquake here, or near here. A few people called so I just want to post that I'm okay. :)

Actually, I was in a restaurant drinking coffee and talking to a friend in Florida when it hit. I told her all about it, she asked how bad was it and I went into a spiel I made up on the spot.

I said something like this:

A 3.0 is a CalPoly 'cause you have to be in the room with a seismograph to notice it. A 3.5 is a Dish Rattler and a 4.0 is a Dog Barker because the dog barks like she does when the garbage truck goes by or a mouse farts behind the baseboard. Cats will hide in the closet and demand that Something Be Done; natural political action committees, most cats.

A 4.5 is a Car Alarm for obvious reasons, though you have to be close by for it to trigger. They sell a gadget to hang on your wall that works just like a car alarm; it scares hell out of you for no reason at the oddest times. And a 5.0 is a Hug-a-Tourist. That's when a perfect stranger in the mall grabs you and hangs on for dear life and you know they're from out of town.

A 5.5 is a Ceiling Check, all the natives and people who've been here for twenty years or more will look up then at the nearest door, just to make sure they know where it is. A 6.0 is a Kneehole, you get down on the floor and scoot under your desk and you pull your idiot friend from Iowa who's still looking at the ceiling under with you. A 6.5 is a T-Shirt Slogan, you can buy one that says, "I survived the such-and-such earthquake" afterwards.

A 7.0 is a Wake-Up-The-Governor to call the National Guard; they may need to go dig some unlucky people out from under collapsed buildings and freeways. A 7.5 is what Californians call a Real Earthquake and of course, an 8.0 is The Big One. The Big One is like Santa Claus, you have the milk and cookies all ready and he never shows up.

So my friend asked me how big was it and was it close? And I said it was about a 5.5, sixty or seventy miles away. Probably east or west of me, I thought, but I didn't say that because she might not have believed me. :) She turned on the TV and found out I was pretty close, they first said a 5.8 in downtown Los Angeles which is 75 miles due west of where I was sitting on the I-10. Later they downgraded to a 5.4.

How did you do that? she asked.

Besides watching everyone in the restaurant look at the door but no one ducked under a table, I counted seismologists, I said. When you first feel the movement, start counting seismologists, (or chimpanzees), when the boom hits that's how far away it is in miles. Then the ground noise begins (a growling sound peculiar to earthquakes and asteroid-size bulldogs), and continues. Keep counting and when the growl dies away, divide by 10, and that's how big the quake is. You can tell direction, sort of, because the first shaking is a circular up-and-down-and-side-to-side perpendicular to a line from the center of the quake to you. The shaking at the peak is back-and-forth between you and the epicenter but it can be hard to tell if you're in a building. That gives you two directions for the quake, 180 degrees apart, like locating a radio signal with a loop antenna. Even standing up outside, you can be thirty degrees off, though. The shaking can go on for a long time after the boom, BTW.

How far away can an earthquake be felt? No one asked, but there's a good rule of thumb for that, too. Take the first number of the magnitude, x, and divide by two, round up, that's n. Now multiply x by the n numbers below it, starting at x-1 down to x-n. So The Big One will be felt 8x7x6x5x4x3 miles away. Basically, all over the earth, more than twenty thousand miles. The quake sound will meet itself coming back from the Indian Ocean, that's why it's called The Big One. A 7.0 in California will rattle dishes in Halifax, though you might not notice since at that distance it will sound like a very long train on the other side of town. A 6.0 in San Diego just misses being noticed in Las Vegas. And a 5.0 in Palm Springs makes the cocktail ice in Santa Barbara clink against the glass.

She asked me how I knew this stuff, did Californians take classes in it. I said, well, they do mention some of this in school but I've lived here 55 years, I figured out the number stuff myself from experience. :)

So, I'm okay. Now we wait to found out if there's going to be aftershocks, the usual situation, or if that was a pre-shock to a bigger quake.

Hugs,
Erin

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