[time-nuts] OCXO shock protection

Chris Albertson albertson.chris at gmail.com
Tue May 21 15:29:17 UTC 2013


The question here, I think was about the day-to-day shaking, not a once in
a lifetime event.   Seriously if there was a 1+g acceleration who'd care if
their OCXO was still running under that pile of rubble that used to be a
house.   It is the days-to-day level stuff that matters to time keeping
even a magnitude 1.0 quake is very rare for any one building even if 1.0 is
common (every day) for a geographic area. The effects are local.

hour-to-hour shaking is caused by building occupants, trucks and
construction equipment and wind.  But mostly things like slamming doors and
such.

Here is a map of recent quakes near where I live.  There are quite a few
but I don't know of anyone who noticed even one last week.  You need
sensitive instruments to detect them over the noise of street traffic and
such.
http://www.data.scec.org/recent/recenteqs/Maps/Los_Angeles.html
All the data are there, you can look up detailed reports of each one  The
web site evenhas a download page where you can get "data" with
accelerations, periods and such.




On Mon, May 20, 2013 at 11:47 PM, Hal Murray <hmurray at megapathdsl.net>wrote:

>
> tvb at LeapSecond.com said:
> > If the quake is strong, the temporal acceleration is on the order of 0.1
> g.
> > See: http://en.wikipedia.org/wiki/Peak_ground_acceleration
>
> There is a long tail on that curve.  One could also define "strong" as 1 g.
>
> The wiki page (above) lists 3 events with PGA above 2 g and several more
> above 1 g.  I remember a USGS report about an event in northern California
> showing a big bulldozer on its side.  The punch line was that the local PGA
> was over 1 g.  (Bulldozers have a low center of gravity.  It's hard to tip
> them over.)
>
> Those are really nasty events.  Distance from the quake (aka luck) is also
> very important.  If you are near one of them you will probably be worrying
> about things other than your OCXO.  (Iterate for what "near" means.)
>
> ----------
>
> > Your OCXO will be fine, unless it falls on the floor.
>
> I agree that falling on the floor is the main thing to worry about.
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
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-- 

Chris Albertson
Redondo Beach, California



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