[time-nuts] OCXO shock protection

Chris Albertson albertson.chris at gmail.com
Tue May 21 11:29:17 EDT 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

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
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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