Dire SF Earthquake Prediction (David?)

[amber]

Okay, my mom said that they say (scientists) if there's a huge earthquake for SF, the bulk of the financial district could be under 12 feet of glass. Twelve feet!

But then, I don't think that's what happened in the 89 quake. So was it just not big enough? Or were these scientists full of snit?

So i'm thinking - yipes.

[sara1998]

Originally Posted by amber

Okay, my mom said that they say (scientists) if there's a huge earthquake for SF, the bulk of the financial district could be under 12 feet of glass. Twelve feet!

But then, I don't think that's what happened in the 89 quake. So was it just not big enough? Or were these scientists full of snit?

So i'm thinking - yipes.

Here's my unscientific conclusion... just get the hell out of northern California! That earthquake business would scare the crapola out of me!

[David]

Originally Posted by amber

Okay, my mom said that they say (scientists) if there's a huge earthquake for SF, the bulk of the financial district could be under 12 feet of glass. Twelve feet!

I guess there's a lot of glass in the financial district.

But then, I don't think that's what happened in the 89 quake. So was it just not big enough? Or were these scientists full of snit?

It's interesting to read up on the building codes & how they've been revised over the decades. After all, modeling is only modeling. In general, the bigger the quake, the longer the duration of shaking. That's what brings down structures built or refitted to code. The deadliest damage in the 1989 quake occurred on the Nimitz Freeway: the part that collapsed was built on San Francisco Bay mud rather than rock. Mud & softer alluvial soil jiggle like Jell-O in an earthquake, amplifying the intensity of the shaking.

The Loma Prieta quake was a moment magnitude 6.9; the shaking lasted about 15 seconds. Imagine a much larger quake -- say, an M7.8, about the size of the 1906 quake. Shaking lasted about a full minute in San Francisco. Buildings that can withstand 15 seconds might not be able to withstand shaking that lasts for a full minute or more.

Luckily, quakes larger than that are extremely unlikely on any portion of the San Andreas fault zone. There just isn't enough locked fault to unzip.

So i'm thinking - yipes.

Southern CA is overdue, too. The best you can do is to learn what kind of soil or rock your residence or your workplace is built on. Site response is the name of the game these days. I live on a 1,000-foot mountain or hillside, made of solid rock. When a quake hits nearby, all I feel usually is a single wrenching jolt, followed by stillness.

[chiliD]

Originally Posted by David

Mud & softer alluvial soil jiggle like Jell-O in an earthquake

Known as "liquifaction".

[amber]

Originally Posted by David

I guess there's a lot of glass in the financial district.
It's interesting to read up on the building codes & how they've been revised over the decades. After all, modeling is only modeling. In general, the bigger the quake, the longer the duration of shaking. That's what brings down structures built or refitted to code. The deadliest damage in the 1989 quake occurred on the Nimitz Freeway: the part that collapsed was built on San Francisco Bay mud rather than rock. Mud & softer alluvial soil jiggle like Jell-O in an earthquake, amplifying the intensity of the shaking.

The Loma Prieta quake was a moment magnitude 6.9; the shaking lasted about 15 seconds. Imagine a much larger quake -- say, an M7.8, about the size of the 1906 quake. Shaking lasted about a full minute in San Francisco. Buildings that can withstand 15 seconds might not be able to withstand shaking that lasts for a full minute or more.

Luckily, quakes larger than that are extremely unlikely on any portion of the San Andreas fault zone. There just isn't enough locked fault to unzip.
Southern CA is overdue, too. The best you can do is to learn what kind of soil or rock your residence or your workplace is built on. Site response is the name of the game these days. I live on a 1,000-foot mountain or hillside, made of solid rock. When a quake hits nearby, all I feel usually is a single wrenching jolt, followed by stillness.

Okay, the other night I was watching "Birth of a City" about SF - and I thought I heard them say something like: "And so they filled in ....[something something] and the financial district was born!"

[Richard B]

Being born and raised in SF, they have been giving dire earthquake predictions since 1979. Nothing new and it sells papers and books. I mean come on, of course it's a safe prediction especially considering the serious fault lines running up and down California.

I survived Loma Prieta as well as countless others, far more survived than did not. Besides everyone knows that anything built on sand is a disaster and tradgedy waiting to happen (bye, bye pretentious Marina district). Multi-million dollar homes on sand land fill. Clever.

It's going to take at least a 7.5 8.0 to really bring down modern SF. Once I was on the Muni underground during one. That was weird. Nice to see everyone remained calm and exited above ground without panic. Course, a 5.0 or 6.0 isn't going to jar too many natives anyway. Leave that to the tourists.

[amber]

Originally Posted by Richard B

Being born and raised in SF, they have been giving dire earthquake predictions since 1979. Nothing new and it sells papers and books. I mean come on, of course it's a safe prediction especially considering the serious fault lines running up and down California.

I survived Loma Prieta as well as countless others, far more survived than did not. Besides everyone knows that anything built on sand is a disaster and tradgedy waiting to happen (bye, bye pretentious Marina district). Multi-million dollar homes on sand land fill. Clever.

It's going to take at least a 7.5 8.0 to really bring down modern SF. Once I was on the Muni underground during one. That was weird. Nice to see everyone remained calm and exited above ground without panic. Course, a 5.0 or 6.0 isn't going to jar too many natives anyway. Leave that to the tourists.

Thanks, that calmed me down...
I hope the Hayward fault doesn't go, because that one is essentially right next to my house....It hasn't gone since 1856 or something...

- I know, the Marina! Bwah! I shouldn't giggle a little, but I am....

[amber]

Originally Posted by sara1998

Here's my unscientific conclusion... just get the hell out of northern California! That earthquake business would scare the crapola out of me!

That's actually what I am thinking about most of the time. It won't be convenient to move for a few years, though...But I'm pretty scared, too. I'm glad I don't drive over the bridges hardly ever, b/c that is the scariest place to me. The bay bridge collapsed last time.

[Richard B]

Originally Posted by amber

That's actually what I am thinking about most of the time. It won't be convenient to move for a few years, though...But I'm pretty scared, too. I'm glad I don't drive over the bridges hardly ever, b/c that is the scariest place to me. The bay bridge collapsed last time.

Oh sweet Amber. The odds of being on a bridge during a earthquake are so remote. I mean really remote. It's not worth stressing about it. Your chances of getting in a car accident on a bridge are much, much higher.

And if you do happen to be on a bridge during a big quake, for smart's sake, don't turn your car around and drive back in a panic like those fools did. Get to treasure island instead...that part of the bridge (on either side) is a more stable part of the bridge. Keep cool and keep your head about you.

But again, chances are it will never happen to you. Never.

Carry on.

[sara1998]

Originally Posted by amber

That's actually what I am thinking about most of the time. It won't be convenient to move for a few years, though...But I'm pretty scared, too. I'm glad I don't drive over the bridges hardly ever, b/c that is the scariest place to me. The bay bridge collapsed last time.

Was it the bay bridge that collapsed in '89? Is that the double decker bridge?

[DavidMn]

God love California, but that's why I live here in flyover land Minnesota. At least all we have to worry about here is tornadoes.

[sara1998]

Originally Posted by DavidMn

God love California, but that's why I live here in flyover land Minnesota. At least all we have to worry about here is tornadoes.

All we have to worry about? They scare the **** out of me. I hunker down every time we have watches issued.

[Richard B]

Originally Posted by DavidMn

God love California, but that's why I live here in flyover land Minnesota. At least all we have to worry about here is tornadoes.

Exactly. Mother nature is everywhere. Seems to me devastating tornadoes are far more frequent than a big quake. You can have it. I'll take a quake anyday.

Besides, I rather like a good jolt. It's very exciting...something that won't hurt anyone...like a 5.0 or 6.0.

[amber]

Originally Posted by sara1998

Was it the bay bridge that collapsed in '89? Is that the double decker bridge?

Yes, exactly. It's the most driven here, too. I also am scared that I will be on BART which is the transit line that goes under the water to SF...nothing happened to it last time, but the thought of being trapped under water during an earthquake scares the mip out of me.

[amber]

Originally Posted by Richard B

Exactly. Mother nature is everywhere. Seems to me devastating tornadoes are far more frequent than a big quake. You can have it. I'll take a quake anyday.

Besides, I rather like a good jolt. It's very exciting...something that won't hurt anyone...like a 5.0 or 6.0.

There's also a giant portion of California that is awesome and not in much danger from earthquakes. I grew up in those places....*sighs nostalgically*...