OT -- attn SF Bay Area members

**BikeMomma** · 10-23-2005, 08:39 PM

This website page may be interesting to you. http://quake.usgs.gov/research/3Dgeologic/

I'm an earthquake geek. Any stories to tell about the Loma Prieta quake? I'm interested to hear them, your personal experiences, etc. Northridge quake stories welcome, as well, for those of you SoCal members.

The world geological events since the Indonesia quake last December have been intriguing me constantly. Awesome stuff.

-BikeMomma

**aka_kim** · 10-25-2005, 09:58 AM

BM (oops! I mean BikeMomma!) - thanks for the link, it is interesting stuff. I think I'll use the shaking hazards/intensity info to try to convince my manager why it's just too dangerous to go visit clients in SF! (I'm only half joking - the thought of being on BART or in the city, lugging around 20 pounds of laptop and assorted cr*p, when the Big One hits... shudder.)

I'm a lifelong CA resident, but I've only experienced one of the bigger quakes (Sylmar in '71). The scariest for me was Sierra Madre in '91, which was only 5 point something but the epicenter was only a few miles from where I lived. I was in the shower, without my contacts in, getting thrown against the sides of the stall. Being naked and blind in an emergency isn't fun.

**SadieKate** · 10-25-2005, 10:12 AM

Kim, where were you in Sylmar '71? I was in Oxnard getting thrown off the top bunk bed to provide a safe landing pad for the books flying off the bookshelves. Discovered that there is a downside to being a reader.

**Trek420** · 10-25-2005, 10:54 AM

can we merge this map with the one of TE members?

Trek-livin'-on-the-faultline-420

**bikerz** · 10-25-2005, 12:19 PM

I'm trying not to let this stuff freak me out too much! The last two teeny weeny quakes on the Hayward fault (3.something and 4.something) were within 2 miles of my house...

For the earthquake geeks out there: My office-mates are part of a team working on a GIS-based earthquake modeling application (in beta now with CalTrans) for the Fed Hwy Admin that analyzes and maps effects of highway and bridge collapses in the Bay Area based on statistical earthquake simulations. So there is just a little too much talk about earthquakes here in our downtown SF office! The application is called Redars - some more info here for the true geeks!

**aka_kim** · 10-25-2005, 01:04 PM

I was asleep in my bed in Glendale when the Sylmar quake hit (I was just a wee, wee thing, you know

). I learned from this quake never to put shelving directly above my bed -- in this case it wasn't books falling on my head, just the knickknacks you collect as a kid.

Redars looks interesting, but collapsing bridges (and tunnels) is another thing I'd like to remain in blissful ignorance about. More reasons to hole up at home and never come out.

**SadieKate** · 10-25-2005, 01:44 PM

That's right, you were still in a crib.

**bikerz** · 10-25-2005, 02:41 PM

Originally Posted by aka_kim

Redars looks interesting, but collapsing bridges (and tunnels) is another thing I'd like to remain in blissful ignorance about. More reasons to hole up at home and never come out.

Apparently, according to some of the seismic experts loafing around our office these days, the Caldecott Tunnel is not a bad place to be in case of earthquake (I've been offered a chance for a guided tour from an old-timer who knows the ins and outs of the tunnel ventillation and so on - just not sure I want that much info!) However, stuck on a BART train under the Bay - no way!!!

After the Katrina fiasco, I've upgraded my planned earthquake kit to "suffcient to live on the front patio for a month"! Now I just have to buy all that stuff... Every weekend I say "Another weekend without getting the earthquake kit put together", to which my SO says "Another weekend without an earthquake!"

**Irulan** · 10-25-2005, 05:57 PM

Loma Prieta - we were living in Concord at the time, hubby was working in Emeryville. Being a consulting geologist, they all thought the shaking was pretty cool. BART was down, and he got a ride home in some day laborer's pickup that had a full load from the station- power broker and grunt alike.

My good friend stayed late at her office; she would have normally been on that stretch of Nimitx that collapsed. Her hubby was on the Bay bridge, just a few hundreds yards ahead of the section that blew out...he said it sounded like gunfire.

Now, all I have to do is worry about volcanic ash.

~Irulan

**SadieKate** · 10-25-2005, 06:23 PM

Yes, the Ring of Fire in the Cascades - it's getting hot!

Sidebar now -- hubby is a geologist? Can he answer a question for me? I'm reading John McPhee's book "Assembling California" and he keeps referring to "country rock." What is it? Googling, of course, produces only music references. Thank you!

Back to earthquake discussions!

**DrBadger** · 10-25-2005, 08:20 PM

Hey SK-
From another geologist (actually geophysics grad student)... country rock is the rock that an ingenues intrusion intrudes into. So, in CA it would be the rocks that were there before the big intrusions that formed the Sierra's and Yosemite and all the pretty stuff. Does that help? Also, here is a web site with a lot of geology terms defined: http://volcano.und.edu/vwdocs/glossary.html

PABadger

**SadieKate** · 10-26-2005, 07:39 AM

Ah ha! Thank you, PA! Does it always take an igneous intrusion to term it Country Rock? Could there be a different type of intrusion?

I'm reading the book because yellow and I were down at the LBS and she and the LBS starting talking geology. Turn out he was a PhD student in Geology before he gave it all up for the bicycle retail world.

**DrBadger** · 10-26-2005, 10:06 AM

I don't think that it has to be an igneous intrusion, that is just the most common. One of my geologic dictionaries also says that it can be the rock surrounding a mineral or ore deposit. So, basically it is the rock that is intruded by pretty much anything, though you don't get intrusions of sedimentary rocks, and many metamorphic are due to the intrusion of igneous rocks.

I am always amazed at how many geo people there are out here... not quite like this in the midwest where I grew up!

**SadieKate** · 10-26-2005, 10:14 AM

Cool. I'll have to back up a chapter or two. Back to the world of batholiths and lithospheres. When we drove down I-80 from Truckee a few weeks ago, Yellow had a sharp eye out for all the stuff McPhee talks about in his book. Me? I just concentrated on not throwing up.

**Deanna** · 10-26-2005, 10:29 AM

I've experienced quite a few small ones--usually too small to do anything like take cover, but enough to get everybody talking. The two largest in my memory are the Loma Prieta and a midnight quake up here on the Rogers Creek Fault about a year ago.

During the Loma Prieta I was working in a cafe in Petaluma. I had just started cutting a lasagna when the quake started. As I was cutting in kind-of a sawing motion, the shaking of the work table seemed to be my fault--my coworkers just looked at me and said "Deanna, what the h#$@ are you doing over there?" We noticed the lights shaking and realized it had been a quake. Being pretty far removed from the epicenter, we didn't realize how bad it was until we got home to watch the news.

The Rogers Creek quake wasn't nearly as large, but it was centered only 5 miles from my home and only 1/2 a mile from my sisters home. This quake produced a large BOOM that woke up most people in the area and then the shaking started. My sister called a few minutes later scared out of her wits. They lost some stuff off of their shelves and her boyfriend was trying to walk when it hit--that didn't work, he fell but wasn't hurt.

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