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Only in your (extremely small) mind.The best way is a laser interferometer for small displacements and GPS or
gross measurements.
Adding a +/- nanometer error to a +/- meter error just gives you a +/-
meter error.
GPS wouldn't be useful for the actual data.
Mounting a conventional strain gage just at the ends would give youString a wire back and forth across / along a fault line to measure
very small displacements in the earth's surface. If the resistance
and/or tensile strength needs to be higher than a common single alloy
wire then structural steel cable could be wrapped around a insulated
wire with a higher resistivity. It could be temperature compensated
as usual, with another wire of the same length loosely supported
nearby in another leg of the bridge.
An abandoned power line may be good to go if it is properly located.
Good info sometimes comes in small displacements.
Bret Cahill
What you are trying to make is a strain gauge. This scheme wont work because
the gauge has to be attached to the substrate along it's whole length not
just strung up like a power line.
Correcting for thermal expansion would require temperature data overBut attaching it to the earth in any
meaningful way over distance would be next to impossible. Yes, you can
compensate for the temperature coefficient of resistance but how do you
compensate for the change in length due to temperature, coefficient of
expansion, a very different animal.
Adding a +/- nanometer error to a +/- meter error just gives you a +/-I can't see a strain gauge being a
solution for seismic motions.
The best way is a laser interferometer for small displacements and GPS or
gross measurements.
They claim laser interferometry won't work over long distances, i.e.,Only two points need to be attached to the earth with
these schemes.
No, you can't. You won't get a 10 millisecond warning as to when theTake a wooden pencil and very slowly bend it. You will begin to hear
small cracking noises
I can predict that pretty good with strain sensors.
I can predict that pretty good with strain sensors.Take a wooden pencil and very slowly bend it. You will begin to hear
small cracking noises
Depends on how fast you load the pencil. If you load it over severalTake a wooden pencil and very slowly bend it. You will begin to hear
small cracking noises
I can predict that pretty good with strain sensors.
No, you can't. You won't get a 10 millisecond warning as to when the
pencil will break.
It's not really on one face. It's several miles above from what mayNow imagine only being able to place a few surface
sensors on one face
There might be some hope in averages here.of literally millions of cubic miles of complex,
fractured, stressed, moving subsurface stuff.
Geologists seem to be able to make really low confidence predictions.It's like predicting the
weather, but much worse: hopeless.
High humidity = high entropyMove to Mississippi.
Absolutely. You can probably estimate the average time betweenTake a wooden pencil and very slowly bend it. You will begin to hear
small cracking noises
I can predict that pretty good with strain sensors.
No, you can't. You won't get a 10 millisecond warning as to when the
pencil will break.
Depends on how fast you load the pencil. If you load it over several
months or years I'll get at least some warning that it is being
loaded.
The linearity / non linearity allows for even better predictions.
Now imagine only being able to place a few surface
sensors on one face
It's not really on one face. It's several miles above from what may
be a thousands of faces.
No one said it was a easy problem, just that there might be some
additional information to exploit.
Distance metrology needs to get the error down to a few microns over
100 km. Apparently laser interferometry is just for short distances,
even turbulence will mess up the measurement.
The strain sensor might not work for the simple reason the strains
would be so low.
What is the best resolution possible with a bridge?
Another solution might be the World's Largest Seismometer, a proof
mass of hundreds of tons.
of literally millions of cubic miles of complex,
fractured, stressed, moving subsurface stuff.
There might be some hope in averages here.
No, it is not, and seismometers have been mechanically trivial to build forHere's an effort to circumvent massive machined commercial
seismometers with smarter electronics:
http://physics.mercer.edu/petepag/eigen.html
You'll be trying a little harder after a few hours trapped under someTake a wooden pencil and very slowly bend it. You will begin to hear
small cracking noises
I can predict that pretty good with strain sensors.
No, you can't. You won't get a 10 millisecond warning as to when the
pencil will break.
Depends on how fast you load the pencil. If you load it over several
months or years I'll get at least some warning that it is being
loaded.
The linearity / non linearity allows for even better predictions.
Now imagine only being able to place a few surface
sensors on one face
It's not really on one face. It's several miles above from what may
be a thousands of faces.
No one said it was a easy problem, just that there might be some
additional information to exploit.
Distance metrology needs to get the error down to a few microns over
100 km. Apparently laser interferometry is just for short distances,
even turbulence will mess up the measurement.
The strain sensor might not work for the simple reason the strains
would be so low.
What is the best resolution possible with a bridge?
Another solution might be the World's Largest Seismometer, a proof
mass of hundreds of tons.
of literally millions of cubic miles of complex,
fractured, stressed, moving subsurface stuff.
There might be some hope in averages here.
Absolutely. You can probably estimate the average time between
earthquakes. Numbers like 300 +-250 years.