So Sunday was a big day for earthquakes. In the wee hours of the ay-em, we had the West Napa Fault Zone (probably) cutting loose, and then, a bit later in the day, Peru got hit big-time. Thankfully, Peru’s quake was in a sparsely-populated area, and California’s was – well, California. They’ve been dealing with this stuff for half of forever. So while Sunday was dramatic for earthquake happenings, it wasn’t so bad as far as death and destruction.
But Cali got lucky – their quake was pretty small compared to Peru’s. Like, way smaller. The South Napa quake was a mere 6.0 – big, but not unimaginably huge. Peru’s was 6.9, same size as Loma Prieta (and we all know how awful that was).
Okay, you may think. 6.9. That’s not that bad.
Except that’s not how the scale works.
At magnitude 6.0, this quake is classed as a strong quake, but one of the unfortunate diagrams I’m seeing in media reports is that anything between a 6.0 and a 6.9 like the Loma Prieta quake are being lumped together on a bar graph as “strong”. The difference between a 6.0 and 6.9 is profound, and is a reason that we are not hearing about dozens or hundreds of people killed in the event. On the magnitude scale, the amount of energy released increases by about 30 times with each whole number. In other words, a magnitude 7.0 quake is just over 30 times more powerful than a magnitude 6.0, and a magnitude 8.0 is just over 30 times more powerful than a 7.0 (this make an 8.0 around a 1,000 times more powerful than a 6.0).
Those numbers can be hard to picture. So I came up with a bit of an analogy that may help. Picture yourself in a car, headed toward a solid wall (in this scenario, you’re a crash test dummy. Sorry). For the first run, you’re going Magnitude 6. We’ll say that’s 25 miles per hour.
Okay, not so bad.
Now, Wikipedia tells me that a 7 is roughly 32 times larger, so we’ll go with Garry’s 30 figure and see where we end up. Hmmm, math… 25 x 32 … carry the ZOMG it’s 750 mph. We’re headed for a wall at 750 mph! We don’t have a crash test at 750 mph! Here’s the Mythbuster’s doing a 100 mph test and being appalled by the result.
I love how their marker dealios look like earthquake focal mechanism symbols. Very apropos. And if this is what 100 mph can do to a car, you can image 750 mph would leave it, the wall, and half the neighborhood beyond in fragments. No wonder the Bay area was in such bad shape after the Loma Preita quake.
Okay. I hate to look, but we’ve gotta do it. Our next victim car is going to hit the wall at 1,000 times the speed of our first test. So we’ve leapt from 25 mph and a little mild damage to something that could wipe out the entire metro area. It’s certainly a much larger impact than the fastest crash test ever, which was only a paltry 120 mph.
Maybe we should’ve switched to planes, but even then…
So those are some pretty intense differences. It’s why we go from this:
Now that we’ve had this little visualization exercise, I’m going to go crawl into bed and whimper, because I live in a place that expecting a 9.