Earthquake in Bay Area/San Jose not an Earthquake?
Earthquake in Bay Area/San Jose not an Earthquake?
(OP)
http://www.sfgate.com/bayarea/article/Mysterious-S...
Anyone else see this? Interesting if any Eng-Tip members experienced it.
Anyone else see this? Interesting if any Eng-Tip members experienced it.
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.





RE: Earthquake in Bay Area/San Jose not an Earthquake?
RE: Earthquake in Bay Area/San Jose not an Earthquake?
Most likely a bolide no one saw.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Earthquake in Bay Area/San Jose not an Earthquake?
Non of their sensors picked it up, they said some of these events are very local and sometimes do not fit in with usual event symptoms.
RE: Earthquake in Bay Area/San Jose not an Earthquake?
TTFN (ta ta for now)
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RE: Earthquake in Bay Area/San Jose not an Earthquake?
I noticed something like this years ago while working on pinball machines, which is why those devices had several sensors, and of different types for different types of machine movement.
And maybe the sensors ignored it, as they should be setup to ignore a large truck driving by.
RE: Earthquake in Bay Area/San Jose not an Earthquake?
RE: Earthquake in Bay Area/San Jose not an Earthquake?
The completely/only circular motion types that make you dizzy and you think you're having a vertigo attack initially.
Then the 'single jerk' P-wave only style, where everything just creaks one time like the whole place just had a "thermal adjustment".
Then the rolling sea-wave style where you get up/down with an accent of left and right tilting just like sitting in a row boat in 6 inch swells.
And finally the really ugly ones that make you stop and wonder what that loud noise is that's approaching: "Is that a train coming - wait there are no fast trains arou@n#d&&#^@%!)_!)#!)!!!!" They hit like having a rug pulled out from under you followed by large circular motion on the order of a foot or two of diameter with a serious 12 inch rolling swell overlaid.
Don56; You could have something there. There is major angst around here. It could've been the head beating reaching some sort of resonance briefly.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Earthquake in Bay Area/San Jose not an Earthquake?
The strongest quake that I've experienced personally was the Northridge quake in 1994. Now we were about 45 miles from the epicenter but it was still a pretty good shake. Our two oldest sons had an apartment about another 10 miles closer and they had actual damage like kitchen cabinets breaking loose from the ceiling and bigger things falling over. We only had maybe one picture fall over and no real damage except a few cracks in the ceiling that got a bit more noticeable.
As for the frequency of quakes here in SoCal, it's a daily event, just that you don't feel most of them. Note that I also have a 'quake' app on my iPhone that keeps me up-to-date in almost real time (I get a 'message' type notice for any event over 3.0 that hits anywhere in California).
As of this moment, here's what's been happening locally for the last few days:
Note that Yellow squares are within the last week and the Blue ones in the last 24 hours. There were no Red ones, which would have been in the last hour. Also, the size of the squares indicate the magnitude. Everything you see on that map was less than a 2.0 (for the record, we live just above the first 'a' in 'Santa Ana' on that map). The 'red lines' on that map are the KNOWN faults.
John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: Earthquake in Bay Area/San Jose not an Earthquake?
RE: Earthquake in Bay Area/San Jose not an Earthquake?
I was doing the dishes in my apartment, and suddenly felt woosy (it was actually the ground moving laterally under my feet - the P waves). I looked over at my ex, and was about to say "did you feel that?" Just then, the S- waves came on, and rattled everything up and down for a bit.
From growing up in San Jose and all the earthquake drills, we made a bee-line right outside once I understood what was happening, but my first thought was that I was just weak-kneed from just standing up too long!
It was really neat to experience the text-book P- and S- waves first hand (and safely :) )
RE: Earthquake in Bay Area/San Jose not an Earthquake?
In the Loma Prieta Quake, which was nowhere near Loma Prieta, but actually over in the middle of The Forest of Nisene Marks, every thing facing in one direction was launched sideways and nothing perpendicular was bothered. You could go thru the house and see it plainly. Pretty fascinating.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Earthquake in Bay Area/San Jose not an Earthquake?
John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: Earthquake in Bay Area/San Jose not an Earthquake?
Keith Cress
kcress - http://www.flaminsystems.com
RE: Earthquake in Bay Area/San Jose not an Earthquake?
I don't do a lot of riding around hands-off these days either, but I remember that when I did, I got best control by sitting as upright as possible as soon after letting go of the bars as possible. Time spent still bent over, with the potential to knock things accidentally, was always a bit wobbly.
Could never bring myself to ride hands-off on a tandem - mine never had quite enough natural damping and on the one I borrowed to take a girlfriend for a week's touring round the Cotswolds, you really did need to ride with both elbows locked the whole time.
but I digress......
A.
RE: Earthquake in Bay Area/San Jose not an Earthquake?
One time I had heard on my morning commute that it was still up in the air whether the Shuttle would land in Florida or California because of uncertain weather at the Cape. When we heard the sonic boom, I said to my visitors, "I guess it's still raining in Florida!" and got the strangest looks!
RE: Earthquake in Bay Area/San Jose not an Earthquake?
Be aware that's a function of bicycle geometry, too, and unless you're using the same exact bicycle you did years ago, you may be mistaking a difference in bike geometry for a change in ability.
RE: Earthquake in Bay Area/San Jose not an Earthquake?
Funny aside: It had a cracked rear strut that I took to a guy to TIG weld. When the guy struck his first arc it welded every single slide cable into their housings.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Earthquake in Bay Area/San Jose not an Earthquake?
JS is definitely right. Head tube angles and trail/rake values have a big impact on hands-off stability. I have a triathlon bike (super long trail) which can be ridden hands off around corners and obstacles without batting an eyelash, while my track bike with very low trail is scary under full power with only one hand on the bars.