
Turning the Optical Fiber Network into a Giant Earthquake Sensor - teklaperry
https://spectrum.ieee.org/view-from-the-valley/at-work/test-and-measurement/turning-the-optical-fiber-network-into-a-giant-earthquake-sensor
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cmsmith
>A single interrogator can cover some 40 kilometers of fiber, Biondi says, and
monitor a virtual sensor every couple of meters.

Earthquake engineer here. This is the cool part. We've got plenty of data to
detect and locate any given earthquake occurred. And we have maps that show
approximately how hard the soil is under any given site. But the intensity
that any building sees is still only known to +-50%, mostly due to variation
in the subsurface conditions that we don't have enough resolution to model.

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evincarofautumn
Would higher resolution detectors also help us develop better models for
prediction?

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dmix
We're not currently able to predict the actual earthquakes at all, only
probabilities of likelihood on very large timescales. I could see it being
useful to predict future damages to certain buildings/areas based on existing
data, assuming an earthquake happened.

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nitrogen
I've heard that internal buses in high performance aircraft also use time-
domain reflectometry such as this to detect wiring faults before they
interrupt service.

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ehnto
Every now and then I get a bit cynical about technology. Then a phrase like
this appears and I am in awe again.

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stephengillie
> _An “interrogator” installed at one end of the line sends pulses of laser
> light into the fiber and monitors the light that bounces back—the
> backscatter. Changes in the timing of backscattering occur when the fiber
> stretches and contracts—something that happens when the ground moves during
> an earthquake._

Ping-based earthquake detection? Could ping jitter of existing optical
networks be used for this purpose?

I had never thought about thermal and mechanical expansion of fiber optics -
it's in the same vein as LIGO/VIRGO - could we one day see a fiber optic
network used for both data transmission and gravity wave detection?

(I once ran fiber about 200 feet through a welding shop, to connect an ancient
PlasmaCAD to a null modem. But we couldn't get the fiber in a spool of less
than 500 feet, so it was mostly a spool in the office.)

~~~
zw123456
Ligo/Virgo uses a number of extraordinary means to cancel out things like
earthquakes or rumblings, local vibrations and so on. But I wonder if you had
1000's of mile of fiber in disparate parts of the world if it would be
possible to cancel out the noise and see gravitational waves? Probably not,
shrug. But still I find it a fascinating thought. Also, cool idea to measure
earthquakes.

~~~
stephengillie
One team's signal is another team's noise?

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snerbles
Fiber-Optic Intrusion Detection Systems (FOIDS) are often used in physical
fenceline security [0], with permanent installations using hardened conduit or
impromptu setups of kevlar-jacketed fiber, zip-ties and concertina wire. It's
only natural that longer runs of fiber can be used for similar vibration
measurements.

[0] Examples at
[https://fibersensys.com/product/fd322](https://fibersensys.com/product/fd322)
and [http://senstar.com/products/fiber-
optic/](http://senstar.com/products/fiber-optic/)

~~~
doribak
No only that protection of pipeline use the same method of monitoring existing
fibers for communication with system like this
[http://www.rbtec.com/products/Pipeline-Protection-
Security-S...](http://www.rbtec.com/products/Pipeline-Protection-Security-
System/RaySenseLeakDetection)

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tzahola
What happened with this HDD-based solution?
[https://www.newscientist.com/article/dn10037-hard-drive-
wobb...](https://www.newscientist.com/article/dn10037-hard-drive-wobbles-
track-earthquake-spread/)

~~~
eric_h
Everyone switched to SSDs ;)

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Moseman23
Seems like the possibilities are endless. When Skynet takes over, this is how
they will hear us coming to switch them off.

