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Re: Hey CA SGTers! What's Shakin'?

Posted: Tue May 19, 2009 10:01 am
by turkeyham
Seriously, I thought there was a large plane taking off from Los Alamitos Reserve Base. It was a loud rumbling sound and then I heard allot of cracking of wood. I live in a condo complex that was build in the 60's. It had been retrofitted 20 years ago and it has held up to some large earthquakes. It's scarry when I live on the bottom floor.

Remember: Aim for the hallway and be under something strong. If you walk under the doorway that has no doors, that is the strongest built area.
I would hide under the desk, but it is near my sliding door and that would be dangerous. :(

Re: Hey CA SGTers! What's Shakin'?

Posted: Tue May 19, 2009 11:28 am
by Big Wallaby
The way you describe this, it sounds like a sonic boom when the Shuttle goes over.

Never ceases to amaze me how the Richter Scale system works. You won't really feel anything under a 4 unless you're in exactly the right place at the right time. You might miss a six if it's short enough, and a 7 can do significant damage to your house.

Anyone (felinefan) know why the scale is set up as it is?

Re: Hey CA SGTers! What's Shakin'?

Posted: Tue May 19, 2009 11:33 am
by hobie16
Big Wallaby wrote:Anyone (felinefan) know why the scale is set up as it is?
It's a base-10 logarithmic scale.

Re: Hey CA SGTers! What's Shakin'?

Posted: Tue May 19, 2009 5:59 pm
by felinefan
Hobie's right. For every tenth of a point, the force of the quake is ten times stronger, i.e. a 5.0 quake is 30 times stronger than a 4.7. For every point the force is 100 times stronger, i.e., a 6.0 is 100 times stronger than a 5.0 . Strongest quake in the world was a 9.5 off the coast of Peru, May 22, 1960. It caused the earth to ring like a bell--shockwaves were recorded worldwide.

The strongest in the U.S. was a 9.2 on Good Friday, March 28, 1964, in Prince William Sound, Alaska. There were more fatalities from tsunamis than from the shaking.

I think the strongest in California so far was the 1857 Fort Tejon quake; I believe it was an 8.75. There was only one fatality when a woman was killed in the collapse of an adobe building. Not a whole lot of damage, either, because of the relatively low population of California at that time.

Though I once read somewhere that Dr. Charles Richter came up with the point scale to answer the questions from reporters when they kept asking him how strong the latest quake was.

Re: Hey CA SGTers! What's Shakin'?

Posted: Wed May 20, 2009 1:30 am
by Big Wallaby
I knew about it being 5.0 a hundred times stronger than a 4.0, but it seems that that leaves a lot of variance available... or accuracy lost.

Re: Hey CA SGTers! What's Shakin'?

Posted: Wed May 20, 2009 5:16 pm
by felinefan
The site explains it better than I can.

Re: Hey CA SGTers! What's Shakin'?

Posted: Sun May 24, 2009 3:22 am
by Soundwave
That was pretty crazy, I had just got off work too. Kinda glad I wasn't there.