# Earthquake at 8:10 in Central CA



## DeniseM (Oct 30, 2007)

We are about 100 miles from the Bay Area, but we just had a pretty good shaker in Modesto - anyone else feel it?

It looks like it was a 5 or 6 in the Bay Area - map


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## TravelSFO (Oct 30, 2007)

The 8:05pm quake measured 5.6 on the Richter scale and was centered in Alum Rock (San Jose).  We felt it slightly in San Francisco.

http://pasadena.wr.usgs.gov/shake/ca/archives.html


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## DeniseM (Oct 30, 2007)

Our wooden shutters rattled and lights swung for several seconds (10-15) and there was a distinct rolling motion.  Whew..... 

I was at the World Series during the Loma Prieta earth quake in San Francisco...so I am probably just a little more nervous than I should really be.


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## brp (Oct 30, 2007)

We're perched on a hillside in Saratoga, and it was quite substantial here. Part of the house is attached to the deck and held by supports into the hillside. I was in one of those rooms when it hit...and moved into the "stable" part of the house 

All is well.

Cheers.


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## IngridN (Oct 30, 2007)

I felt it also.  About 20 miles away.  DH is off on business travel and I was talking to him when it hit.

Interestingly, the USGS website categorizes it as light shaking because there was no damage although, personally, it felt more like moderate shaking to me!

Ingrid


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## DeniseM (Oct 30, 2007)

This is an interesting map - for some reason, we got a pretty good jolt in Modesto - the colors indicate the intensity.  Not sure why.  We are 70 or so miles away, on the other side of a mountain range, but we really felt it here, although we don't have a major fault line.


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## ricoba (Oct 30, 2007)

The internet is amazing, I just read the headline on Drudge about the quake and Tuggers already giving personal experiences!!! 

Sure hope all of you up there are OK....please don't send it south OK?


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## Denise L (Oct 31, 2007)

Here in San Jose, we are pretty close to the Alum Rock area. It shook the house harder than any CA earthquake I can recall (even more than the one that knocked the freeways down years ago). Two Disney figurines fell off a shelf, hit the wall, and broke.  Water sloshed out of our small fish tank. My daughter was doing homework and I was gathering up recyclables for garbage night. I had enough time to register the quake, and call (okay, yell) for her to stand under the doorway arch with me, and it was still shaking. Very noisy one for us. My husband pulled my son out of the tub, wrapped him up, and got under a doorway upstairs. 

I am still a bit unnerved, not unlike when the HA pilot flew into OGG like madman last December.

Waiting for aftershocks...


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## ricoba (Oct 31, 2007)

Denise L said:


> Waiting for aftershocks...



Let's hope they are small and that there are very few.  

I know the last time we had a little shake down here in LA, I was awake the rest of the night waiting for the just in case aftershock.


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## applegirl (Oct 31, 2007)

Wow, you guys are amazing! I missed the ticker tape message earlier tonight about an earthquake and then I learn about it here at TUG. The internet truly is an amazing place.  I hope you guys are all okay up there and I echo ricoba's sentiments, keep it to yourselves if you don't mind. We've had enough to deal with concerning these darn fires! Thoughts are with you.

Take care,
janna


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## Icc5 (Oct 31, 2007)

*In Bed*

I was already in bed because I get up at 2:30 am for work.  It seemed as if this one was going to just keep going and going.  Shortly after I heard the phone ring a few times and figured it was our daughter and the store where we work calling.  Hopefully, I don't walk into a store full of broken items today.
We are about 20 miles from the center of the quake.
Bart


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## T_R_Oglodyte (Oct 31, 2007)

DeniseM said:


> This is an interesting map - for some reason, we got a pretty good jolt in Modesto - the colors indicate the intensity.  Not sure why.  We are 70 or so miles away, on the other side of a mountain range, but we really felt it here, although we don't have a major fault line.



Intensity is much more related to local geology than it is to proximity to the actual earthquake location.  During the 1986 Loma Prieta quake, for example, the most intense shaking occurred in waterfront areas in Oakland and San Francisco, not in the south Bay close to the epicenter.  During the 1904 San Francisco quake, Stockton had much more intense shaking than did areas of San Francisco such as Twin Peaks and Potrero.

See here and here. You felt it more in Modesto because much of the soil in the Modesto area is loose sedimentary soil.  Areas on the west side of Modesto, where there is shallow groundwater, should have had the most intense shaking in the Modesto area.


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## Luanne (Oct 31, 2007)

We definitely felt it.  We're a bit north and east of where it hit.  Being a true "California girl" I knew immediately what it was.  What I didn't know was that whenever there is a quake of 5.0 or larger, there is a greater possibility of a larger aftershock that will occur in the following 72 hours.    The USGS was saying they would have been more concerned if the quake had been on the Hayward fault, which we happen to be right on top of.

Between the fires in southern California and this latest quake, it's just our way of saying "Are you sure you want to move to California?" :ignore:


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## TravelSFO (Oct 31, 2007)

T_R_Oglodyte said:


> Intensity is much more related to local geology than it is to proximity to the actual earthquake location.  During the 1986 Loma Prieta quake, for example, the most intense shaking occurred in waterfront areas in Oakland and San Francisco, not in the south Bay close to the epicenter.  During the 1904 San Francisco quake, Stockton had much more intense shaking than did areas of San Francisco such as Twin Peaks and Potrero.



Composition is also a factor.  The homes in (on) Potrero (Hill), where we are, are built on rock.   We felt some motion but it was very, very minimal.  Let's just say I could not see anything move except for the leaf on our plant.  Not a peep from our animals, either.


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## T_R_Oglodyte (Oct 31, 2007)

TravelSFO said:


> Composition is also a factor.  The homes in (on) Potrero (Hill), where we are, are built on rock.   We felt some motion but it was very, very minimal.  Let's just say I could not see anything move except for the leaf on our plant.  Not a peep from our animals, either.



Composition is local geology. The situation that Potrero Hill is composed of rock *is* the geology of Potrero Hill.


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## johnmfaeth (Oct 31, 2007)

Hi All,

Very glad to hear that it appears minor in damage levels, hopefully no one was injured which is more important.

Luanne's comment made me recall a Johnny Carson monologue of several decades ago. 

Carson was commenting on Jerry Brown wanting to run for President and stated that as Governor, Brown had dealt with Earthquakes, Fires, Medflies, Droughts, et al. His punch line was "this guy clearly has bad luck, who wants him in Washington!!!".

Hope you are through the worst of this stuff for a while and have a quiet, boring spell coming up.


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## Fern Modena (Oct 31, 2007)

You live on Potrero hill?  I used to work at 17th & Mariposa, at the Muni barn (I was a dispatcher).  Small world.

Fern



TravelSFO said:


> Composition is also a factor.  The homes in (on) Potrero (Hill), where we are, are built on rock.   We felt some motion but it was very, very minimal.  Let's just say I could not see anything move except for the leaf on our plant.  Not a peep from our animals, either.


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## debraxh (Oct 31, 2007)

We're in the Almaden Valley area of San Jose (near base of Santa Cruz mountains) and we felt it but it didn't seem very strong.  For us it was a moderate initial boom, followed by a few seconds of mild shaking.  The china cabinet rattled and chandeliers swayed, but that was it.

And the internet is amazing.  Although the phone circuits were busy (both landline and cell) I was able to find the USGS report within 5 minutes that pinpointed the location followed by a report of the magnitude and (no) damage reported.  Pretty cool.


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## TravelSFO (Oct 31, 2007)

Fern, 

17th runs parallel to Mariposa.  Do you mean the barn at 17th and Bryant?  

Btw, there is a Whole Foods here now.  Safeway at the Potrero Center has an entire organic section to keep from losing customers.


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## DeniseM (Oct 31, 2007)

T_R_Oglodyte said:


> Areas on the west side of Modesto, where there is shallow groundwater, should have had the most intense shaking in the Modesto area.




Yep!  We live on the west side of Modesto.


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## Steamboat Bill (Oct 31, 2007)

fires...earthquake....what's next?

I will be in the Bay area in 2 weeks...Hmmm.


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## ricoba (Oct 31, 2007)

Steamboat Bill said:


> fires...earthquake....what's next?
> 
> I will be in the Bay area in 2 weeks...Hmmm.



If we get any rain, it will be mudslides!


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## brp (Oct 31, 2007)

ricoba said:


> If we get any rain, it will be mudslides!



And if we don't get any, it will be drought...

Cheers.


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## T_R_Oglodyte (Oct 31, 2007)

Steamboat Bill said:


> fires...earthquake....what's next?
> 
> I will be in the Bay area in 2 weeks...Hmmm.



Volcanoes?? Floods??  Tsunami??


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## Luanne (Oct 31, 2007)

Steamboat Bill said:


> fires...earthquake....what's next?
> 
> I will be in the Bay area in 2 weeks...Hmmm.



Ahhh, you won't have to worry.  We've had it all now.


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## T_R_Oglodyte (Oct 31, 2007)

Luanne said:


> Ahhh, you won't have to worry.  We've had it all now.


I would have suggested alien invasion, but the city canceled the annual Halloween street party in the Castro.


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## Luanne (Oct 31, 2007)

T_R_Oglodyte said:


> I would have suggested alien invasion, but the city canceled the annual Halloween street party in the Castro.



Yeah, it will be interesting to see how that plays out.  Do _they_ really think no one will show up?


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## Fern Modena (Oct 31, 2007)

You can tell I moved away.  The barn is on Mariposa & Bryant.  Where's the Whole Foods?  I remember when the Safeway shopping center opened, and when the Costco opened nearby.  We used to sneak out on weekends to get hot dogs for lunch (when we weren't running downstairs to buy tomales or ice cream from the vendors).

Fern



TravelSFO said:


> Fern,
> 
> 17th runs parallel to Mariposa.  Do you mean the barn at 17th and Bryant?
> 
> Btw, there is a Whole Foods here now.  Safeway at the Potrero Center has an entire organic section to keep from losing customers.


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## debraxh (Oct 31, 2007)

Did anyone else feel the aftershock around 3:55pm today?  Several of us in the office (in Cupertino) felt something and sure enough, same spot as last night and it was a magnitude 3.7.


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## TravelSFO (Oct 31, 2007)

Fern Modena said:


> You can tell I moved away.  The barn is on Mariposa & Bryant.  Where's the Whole Foods?  I remember when the Safeway shopping center opened, and when the Costco opened nearby.  We used to sneak out on weekends to get hot dogs for lunch (when we weren't running downstairs to buy tomales or ice cream from the vendors).
> 
> Fern



That huge empty lot at 17th and Rhode Island -- yes, the entire block! -- is Whole Foods and its parking garage on the 1st and 2nd floors.  Condos up above.


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## LisaH (Oct 31, 2007)

Darn, I missed the whole thing! Last night, I just got back from San Diego and was in the car leaving SJC airport. The news lady announced on the air that she just experienced an earthquake. Since I was about to get on the freeway, I didn't pull aside and stop. I tried to call my hubby and the cellphone didn't work! I guess too many people were calling at the same time.


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## LisaH (Oct 31, 2007)

I didn't notice the aftershock this afternoon either. Do you work for Apple or HP? I live in Cupertino.



debraxh said:


> Did anyone else feel the aftershock around 3:55pm today?  Several of us in the office (in Cupertino) felt something and sure enough, same spot as last night and it was a magnitude 3.7.


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## T_R_Oglodyte (Oct 31, 2007)

LisaH said:


> I didn't notice the aftershock this afternoon either. Do you work for Apple or HP? I live in Cupertino.



On a Saturday a few weeks after the Loma Prieta quake a group of us were working in our offices in Walnut Creek.  I was listening to the Stanford game on the radio. The announcers suddenly stopped announcing the game and said they were having a significant aftershock.

I got on the office intercom and told people to get ready for an aftershock.  About 30 seconds later it hit.

Some of my co-workers were amazed at how I knew it was coming.  I did 'fess up.


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## Fern Modena (Oct 31, 2007)

Well, since we are talking about earthquakes, here's my experience from The Quake of 1989.  Its a report I did for work after the earthquake.  It was part of my department's report on the quake, and later became part of The City's permanent archive.  If you read down the page, you'll see that Jerry did a report, too.

Fern


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## Phill12 (Nov 1, 2007)

*Shaker*

We were up in Lake Tahoe enjoying some of our bonus days at the Ridge Tahoe. Our daughter called from her computer class in Lathrop to tell us what happened!

 Said it went about 45 seconds and moved tables and computers around pretty good!

 We went through some good size ones living in Half Moon Bay Ca for years but she said this was just as bad as any of those!


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## bailey (Nov 1, 2007)

*earthquake*

I sure felt it in Stockton!  I know have a large crack in my dining room wall that I don't remember being there before last night.


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## debraxh (Nov 1, 2007)

LisaH said:


> I didn't notice the aftershock this afternoon either. Do you work for Apple or HP? I live in Cupertino.



HP - how did you guess?


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## LisaH (Nov 1, 2007)

debraxh said:


> HP - how did you guess?



Well, I figure Tuggers are all smart folks who will only work for the best companies in Cupertino


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## John Cummings (Nov 5, 2007)

T_R_Oglodyte said:


> Intensity is much more related to local geology than it is to proximity to the actual earthquake location.  During the 1986 Loma Prieta quake, for example, the most intense shaking occurred in waterfront areas in Oakland and San Francisco, not in the south Bay close to the epicenter.  During the 1904 San Francisco quake, Stockton had much more intense shaking than did areas of San Francisco such as Twin Peaks and Potrero.
> 
> See here and here. You felt it more in Modesto because much of the soil in the Modesto area is loose sedimentary soil.  Areas on the west side of Modesto, where there is shallow groundwater, should have had the most intense shaking in the Modesto area.



Santa Cruz was hit very hard by the 1989 Loma Prieta earthquake.


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## T_R_Oglodyte (Nov 5, 2007)

John Cummings said:


> Santa Cruz was hit very hard by the 1989 Loma Prieta earthquake.



Yes, Santa Cruz was hard hit, but the highest intensities occurred on the Oakland, Emeryville, and Berkeley waterfront areas.  The bedrock formations in the Bay area created a focal point for the seismic waves in that area.

There was a perfect storm combination of loosely placed and uncompacted fills, shallow ground, and the focusing of the waves.  Five miles north or south of the Emeryville area along the waterfront, the intensities dropped greatly, even though the other conditions were identical.  That's because the waves were focused in the Emeryville area.

At the time the quake hit I was in Emeryville, in a car stopped in traffic on Shellmound Street, one half block north of Powell.  I saw waves moving across the ground surface that were three to four feet high, peak to trough.  I also observed that the waves were coming from several different directions.  I made specific note of that because of that is unusual - seismic waves are start at the epicenter and move outward in a progression, just as sound waves do. 

I puzzled at the time and for several years afterwards about why I had observed that.  When the seismological studies of the quake were published it became clear.  I was in the focal zone and the waves were coming from different directions as they reflected off of the bedrock.


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