Rocking 'n rolling in the Bay area

Tom · Oct 31, 2007

Around 8.04pm yesterday a moderate earthquake hit the San Francisco Bay area. A 5.6 on the southern Calaveras fault, with the epicenter in the Alum Rock area of San Jose. Most of the shock propagated south and southeast, so we felt relatively little here.

I just got off the phone with Chris Pennings. He and Mimi would have been in the line of shock. They're both OK with no damage to people or property.

No reports of injury in the area and most property damage appears to be limited to broken glass and stuff falling from store shelves. Worst hit appears to have been Reid Hill View airport, where the window(s) in the control tower popped.

I was watching TV and felt a slight rocking of the recliner. I turned around, thinking Chris was rocking the back of the chair, but realized she was in the kitchen. I then looked at a plant alongside me and realized it was rocking a little. Just about then, Chris said "we're having an earthquake". I replied "it's just a small tremor".

The USGS is concerned that the jolt was so close to the junction of the northern Calaveras fault and the Hayward fault that it could have transferred stress to those faults, loading them up for a potential release. The Hayward fault is the one that threatens widespread damage and loss of life in the Bay area.

I vividly recall when the Loma Prieta quake hit; The sound was deafening and the walls of the house were flexing pretty good.

ArdraF · Oct 31, 2007

Glad it was just a small one!

Hmmm, and they built Cal State Hayward right on top of the Hayward Fault. Could never understand that...

I then looked at a plant alongside me

We used to have a light hanging from the ceiling over the dining room table. That was my earthquake sensor. It went wild during Loma Prieta.

ArdraF

Ron · Oct 31, 2007

Glad you and the Pennings are OK with no damage. Earthquakes can be scary even when they do not do serious damage.

Tom · Oct 31, 2007

That's true Ron. The Loma Prieta quake was a scary one for me. After the awful noise subsided and the walls quit acting like jello, power, traffic lights, phones and cell towers were all out, and I had no way of knowing if Chris was OK until she eventually arrived home. Meanwhile, we evacuated to the motorhome, fired up the generator and watched the news reports on TV.

Ron · Oct 31, 2007

I know a few folks that evacuated to their MH or 5ver during earthquakes.

Shayne · Oct 31, 2007

Glad you are safe

Ron · Oct 31, 2007

When we lived in Tokyo we experienced several small earthquakes. The general feeling was as long as they happen frequent enough they don't get too bad. The gas meters all had automatic shutoffs on them and the trains would stop if the earthquake reached a predetermined level.

Shayne · Oct 31, 2007

If they got worst the the determined level they'd probably stop on their sides anyway.

Tom · Oct 31, 2007

Ron said:
... and the trains would stop if the earthquake reached a predetermined level.

That's automatic procedure for the BART system in the Bay area and I believe for regular trains. They are required to check the tracks before allowing trains to continue and BART is also required to check the trans-Bay tube.

I've seen some horrifying video of large earthquakes in Tokyo. Really scary.

Ron · Oct 31, 2007

Tom said:
That's automatic procedure for the BART system in the Bay area and I believe for regular trains. They are required to check the tracks before allowing trains to continue and BART is also required to check the trans-Bay tube.

I've seen some horrifying video of large earthquakes in Tokyo. Really scary.

Fortunately the ones that occured while we were there were not real distructive. I think they only had to reset our gas meter a couple times. And only once or twice did Sam's plates or decorations move.

ArdraF · Oct 31, 2007

I'll never forget Christmas morning of 1949 when we had a humdinger in Tokyo. Our Christmas tree waltzed all the way across the living room. Meanwhile we all ran outside, except for our houseboy Tanaka who said no worry as long as it goes sideways. Said he'd go outside if it went up and down - meaning the building would bounce off the foundation. I'd still rather have an earthquake than wildfires, tornados, or hurricanes. At least with earthquakes, if serious, you can sift through and find stuff. Can't do that if it's burned or blown away.

ArdraF

Bob Buchanan · Oct 31, 2007

Tom said:
Around 8.04pm yesterday a moderate earthquake hit the San Francisco Bay area. A 5.6 on the southern Calaveras fault, with the epicenter in the Alum Rock area of San Jose. Most of the shock propagated south and southeast, so we felt relatively little here.

Hi Tom:

My Brother lives in San Jose -- and my Niece even closer to Almum Rock in Fremont - and the family was glad to hear they were all OK. When I first moved to the Bay Area and felt my first quake I was of the impression that each step up the scale was 1 unit of energy greater than the preceding number -- e.g., that a 4.0 up to a 5.0 quake was the same as from 5.0 to 6.0. But as you know, it's a logarithmic and scary scale making each number exponentially higher than the last.

Here is a quote from THIS Website that describes the latest formula and corresponding increase in energy as the number goes up. So if the one in San Jose was 5.6, ya would not want to be around if it was a 7.6.

"An increase of 1 step on this logarithmic scale corresponds to a 10 to the 1.5 power = 31.6 times increase in the amount of energy released, and an increase of 2 steps corresponds to a 10? = 1000 times increase in energy."

This latest shake was not felt in the Sacramento area, but I remember well the Loma Prieta quake West of San Jose on the San Andreas fault in 1989 that really caused a lot of San Francisco damage. I felt it for about 20 seconds in Sacramento. HERE is a Website that describes it w/a number of photos. In terms of energy released, this would demonstrate the difference between the 5.6 quake in San Jose to the 6.9 Loma Prieta quake. The number is not that much higher(just over 1 point), but the energy release it represents is exponentially larger.

Ron · Oct 31, 2007

The folks at the airline told me the same thing sideways is better than up and down.

caltex · Oct 31, 2007

I don't know whether it was sideways or up and down, but the Loma Prieta quake emptied out our swimming pool. The water just jumped out. didn't crack the pool though. We were living in Los Gatos at the time, not too far from the epicenter.

At work, we had just moved into a new office building and the eye high partitions defining the individual offices hadn't been fastened down yet. They came down like dominoes. Then all the false ceiling tiles came down. When I got outside, the ground was definitely going sideways - you could not stand up. Hugh trees were flexing more than 45 degrees.

The only good thing about earthquakes and tornadoes - they don't last long.

Ron · Oct 31, 2007

Best thing is living in an area that either Tornadoes or earthquakes are very infrequent or nonexistent.

Tom · Oct 31, 2007

Hi Bob,

Glad to hear that your family is OK.

Interesting reading re the newer quake force scale. I believe newsfolks are still using the Richter scale when they report a 5.6.

....I remember well the Loma Prieta quake West of San Jose on the San Andreas fault in 1989 that really caused a lot of San Francisco damage.

The interesting phenomenon there was the way the peninsula essentially whiplashed, resulting in the extreme damage in the Marina district that was built on landfill and liquified. We had folks traveling on the east coast and they couldn't talk to family in the Bay area due to the phones being out. All they got to see were the CNN newsclips of the devastation in the Marina district. They assumed that, since San Jose was much closer to the epicenter, their homes were in far worse shape than San Francisco, but the opposite was true. They were relieved when they got off planes in San Jose and arrived home.

The Hayward fault lets go on average every 140 years, and we're now at year 139.

KodiakRV · Oct 31, 2007

ArdraF said:
... I'd still rather have an earthquake than wildfires, tornados, or hurricanes. At least with earthquakes, if serious, you can sift through and find stuff. Can't do that if it's burned or blown away.
...

And you can't do it if you're buried under the rubble...

Tom · Oct 31, 2007

Robert,

You were closer to Loma Prieta than we were. I recall you and I checking out George and Joannie 's house on the hill because they were traveling. Quite a mess in their kitchen because the liquor cabinet spilled its contents onto their nice hardwood floor. IIRC this was before their friend Craig replaced the long stilts holding their deck on the steep hill. It could have been a real mess if those stilts gave way or slipped off their piers.

Tom · Oct 31, 2007

KodiakRV said:
And you can't do it if you're buried under the rubble...

Frank, that's one reason that houses in earthquake country are built to be flexible and are bolted to their foundation.

chrpennings · Oct 31, 2007

When the quake hit I was in the garage doing some blue jobs. There was a tremendous noise on the roof and my first thought was that a couple of guys were dancing on my shake roof, (you never know Halloween) I rushed outside but no suspects. Mimi came outside and said that she heard a very hard bang.
During the Loma Prieta earthquake is was on business in Singapore. As soon as I received the news I called Mimi and she said there was no rush for me to come home and only very little damage. It sure scared her she was in the livingroom and the water in the pool was slashing up the windows 2-3 feet high.
We had a modest aftershock this afternoon of 3.7 and about 130 smaller ones.
We still love San Jose and would not change for anything else. It also confirms my strategy when the motorhome is not in storage but on the driveway, keep the fuel and watertank full, booze in the refrigerator and clean underware in the closet

Rocking 'n rolling in the Bay area

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