[time-nuts] Detecting gravity with optical atomic clocks

[Dana Whitlow]

Can anyone point me to a readily-accessible reference that would
address the following largely-intuitive notions that I carry around
with me:
> seismic waves could be resolved into three measurable components
      at the Earth's surface:
   a) vertical motions
   b) horizontal motions along the line connecting the source to the
       observer
   c) horizontal motions perpendicular to the line mentioned in (b)

I'm interested in the rate at which these three (if correct) vary with
frequency and decay with distance.  And, of course, if my intuitions
are significantly in error, I'd like to have them straightened out.

Thanks,

Dana


On Sat, Dec 1, 2018 at 7:47 PM Tom Van Baak <tvb at leapsecond.com> wrote:

> "Paul Bicknell" --
> > Any chance of a picture of your Synchronome pendulum clock and associated
> > timing / logging equipment
>
> Yes, I'll update that page with more info and photos at some point.
> Meanwhile there are some links to follow at the end of the page:
> http://leapsecond.com/pend/synchronome/quake.htm
>
> ----
>
> "Didier Juges" --
> > Tom,
> > I suspect something so sensitive gives you significant "false positives"
> > when a delivery truck goes by. I assume you try to correlate your data
> with
> > other enthusiasts nearby to resolve those discrepancies the way we do
> with
> > our clocks?
>
> The pendulum is directly bolted to large thick basement corner wall. Local
> door slams or delivery trucks have no effect that I've ever seen. But a 7.0
> earthquake is truly massive and it creates ground motion at the many
> microns to mm levels even 1500 miles away. A precision pendulum clock is
> affected by this level of vibration, especially when it persists for many
> minutes.
>
> Yes, the pendulum data correlates in time with professional seismometer
> stations here and around the northwest.
>
> ----
>
> "Hal Murray", "Poul-Henning Kamp" --
> > And can you reverse-engineer the local ground movement from the
> > pendulum measurements ?
>
> For quartz, rubidium, and pendulum clocks, it is possible to partially
> reverse-engineer effects of temperature, pressure, and humidity. These are
> scaler quantities and very slow moving processes.
>
> Seismic effects on pendulums are a whole different problem. It's a 3D
> vector quantity. They are very dynamic (rapidly changing), with a complex
> power spectrum. And the interaction of ground acceleration with a swinging
> pendulum is extremely dependent on angles and on the instantaneous pendulum
> phase vs. seismic power relationship, which is changing every millisecond
> and lasts for minutes. Plus the pendulum reaction to some of these changes
> is non-linear. As Bob would say, lot's of fun.
>
> In theory if you had several pendulums arranged around a circle, and used
> ultra wide band seismometers (or super high resolution accelerometers), and
> took measurements at 10 to 100 Hz, then I suspect computer simulations
> might be able to make some predictions out of the data. Which you could
> then back out.
>
> /tvb
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>