World's Largest Wheatstone Bridge
in [Basics]
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From: Don Klipstein on 4 May 2010 00:53 In <671d96b8-9355-48b0-afdb-1174e7683791(a)a27g2000prj.googlegroups.com>, Bret Cahill wrote: >> >> >>> String 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 >> >> >> Two gps stations on both sides do the same trick >> >> >> > What's the smallest displacement -- not movement but actual change in >> >> > _distance_ between two points -- they can measure? >> >> >> > Bret Cahill >> >> >> They measure continental drift with them in cm's per year.... >> >> >The warning might be in microns. >> >> >Bret Cahill >> >> What warning? Faults creep all the time. > >At constant speed? > >If that were true all the acceleration measurements published by USGS >or Cal Tech on the web in real time would always be zero. > >There may be some characteristic behaviour of certain faults that >could be highly reliable early warning info. > >> Knowing the rate of creep has zero useful predictive value. > >Has this been proven over long distances measuring displacements of a >few thousandths of an inch? I would like to add a couple things: 1: How do you propose to discern signal of "a few thousandths of an inch" from noise including whatever harmless-and-usual deviations of-noise-type from cm-per-year scale plate movement? I would worry more about somewhere having fault movement of a few millimeters within a day transferring stress to "where a big one will come from". If that does not cause a major earthquake within a day, then the "big quake" has fair chance of coming 20-30-plus years later. I would also worry about "a big one" having mere few minutes of advance warning from significant acceleration of detection of "fault slips", along with likely a majority of these being "minor burps" as opposed to "the brown stuff hitting the fan". Not that I want to discourage research in this area... -- - Don Klipstein (don(a)misty.com)
From: jimp on 4 May 2010 01:28 In sci.physics Bret Cahill <BretCahill(a)peoplepc.com> wrote: >> String 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 > > > The problem is just to the East of Laguna Salada: > > http://maps.google.com/maps?f=q&hl=en&q=32.2006,-115.4625(M3.0+-+Baja+California,+Mexico+-+2010+May+04+02:35:27+UTC)&t=h&z=9&iwloc=A > > String a thin steel wire from Aqua Matias to Cucapa returning with a > larger diameter copper wire with a resistance << than the steel. > > All those << M 1.0 movements can now be documented and studied. > > > Bret Cahill Obviously you have no clue what "Wheatstone Bridge" means and are just, once again, throwing out technical terms you think will impress people with your knowledge. -- Jim Pennino Remove .spam.sux to reply.
From: jimp on 4 May 2010 01:31 In sci.physics Bret Cahill <BretCahill(a)peoplepc.com> wrote: >> >String 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 >> >> Differential GPS and laser rangefinders make a lot more sense. > > Laser rangefinders can work over dozens to hundreds of miles in a dust > storm or rainstorm? Hundreds of miles, nope, but when combined with GPS you don't need lasers to go hundreds of miles. > To the nearest few microns? Over hundreds of miles microns are meaningless and in the noise of numerous factors. -- Jim Pennino Remove .spam.sux to reply.
From: Cwatters on 4 May 2010 08:05 "Bret Cahill" <BretCahill(a)peoplepc.com> wrote in message news:1e80670c-07b7-4c3b-8578- >The warning might be in microns. >Bret Cahill Which you plan to measure with string? What advantage does string offer over existing GPS and laser based devices?
From: Cwatters on 4 May 2010 08:08
"Bret Cahill" <BretCahill(a)peoplepc.com> wrote in message news:120c41b8-59e1-438b-91f0-829eeabeb471(a)a2g2000prd.googlegroups.com... >> >String 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 >> >> Differential GPS and laser rangefinders make a lot more sense. > >Laser rangefinders can work over dozens to hundreds of miles in a dust >storm or rainstorm? > >To the nearest few microns? > >Bret Cahill How does string work over hundreds of miles ins a dust storm? |