Californian Members

[Cormanus]

Word has reached Australia that the earth moved yesterday in California.

I hope all Forum members affected are unharmed and safe.

Best wishes.

[Randy B]

It was about 90 miles north of me and the damage was fairly localized. The town of Napa declared a state of emergency ant 7:59 AM local time and the governor did the same shortly after that. There are about 20 water main breaks in the town of Napa hindering some efforts to extinguish fires, but for the most part there is water pressure enough to take care of them. There have been some partial building and structure collapses, but at this time I don't know of any fatalities. I do know there was a young child flown by helicopter to a neurological trauma center due to a chimney collapse and a few people with broken bones, but most of the reports are stating not much more than cuts and scrapes.
They are not cancelling the race at the Sonoma raceway this weekend so there shouldn't be any damage there.
There were also some roadway collapses, but no damage to any of the bridges in the area (as reported).

[emptysea]

Thanks for the update. Glad you're safe.

[Pauley]

I'm in Walnut Creek about 35 miles south of Napa. The 3:20 am quake woke my wife up but I slept through it. No damage here.

In Napa County there was some damage, some power outages and some injuries. The Loma Prieta Quake in 1989 was 6.9. This was a 6.0 - almost an order of magnitude less severe.

Think positive thoughts for those affected.

[Randy B]

I heard on the news that the Loma Prieta quake was 22 times more powerful....wow.

[Cormanus]

Our thoughts are with you all.

[Papa Weeley_imp]

Very nice, Cormanus, thanks for checking in.
Luckily for us, this was about 500 miles north of us for once - here's hoping all is well for everybody up there. So far, report is that some major structural damage was done, but no fatalities, and only 6 seriously hurt - a minor miracle itself.

[PowderToastMan_imp]

I heard on the news that the Loma Prieta quake was 22 times more powerful....wow.

Yeah it's pretty wild to think of it that way but it kind of makes sense since magnitude is on a log scale... the Loma Prieta is listed as 6.9 while this one is 6.0 which means about one order of magnitude difference.

That's not the whole story though, as the depth of the epicenter also makes a difference. So what we really should care about is "intensity" instead of magnitude, because that measures the actual force felt at any given point on the ground.

Deeper epicenter means the power is dissipated over a larger area by the time the waves hit the surface. I'd want to imagine that it should be inversely proportional to the square of the depth, if you think of power dissipation in the absolute simplest way possible, but earthquakes can't be quite that simple. Pretending that it is that simple, than an earthquake of the exact same magnitude but twice the depth would have 1/4 the intensity.

So assuming 22 times more power and half the depth, we get about 4/22 times as much intensity.

"The More You Know..."

And, I did not wake up for this one. I didn't know it happened until I peeked at Bay Area Riders Forum and somebody posed the question, what happens if there's an earthquake while you're riding?