New Strain Meters for Geophysics

King, Geoffrey; Bilham, Roger; Gerard, V. B.; Davies, David G.; Sydenham, Peter H.

doi:10.1038/223818a0

Cited by 19 publications

(7 citation statements)

References 4 publications

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“…Using frequency divider FD 2 with a scaling ratio of 52, the 1620-Hz signal is divided down to 31 Hz. This frequency acts as a reference frequency for two-channel lock-in amplifier SD 4 . The Open output signal is fed via LF filter LFF 4 into the other input of SD 4 .…”

Section: The Second Hf (Seismic) Channelmentioning

confidence: 99%

“…In a double-pass interferometer, the signal phase incursion due to deformation ε(t) along the measuring interferometer arm of length L is (4) where λ = c/ν is the laser wavelength and n is the refractive index of the medium through which the laser beam is transmitted.…”

Section: Laser Interferometer Sensitivitymentioning

confidence: 99%

“…Laser interferometers-deformographs with measuring arms from tens of meters to several hundred meters long were manufactured and operated over different periods of time in the United States [1][2][3], Great Britain [4,5], Italy [6,7], and Japan [8]. Geophysical instruments based on laser interferometers were also developed in Russia.…”

Section: Introductionmentioning

confidence: 99%

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A Laser Interferometer-Deformograph for Monitoring the Crust Movement

et al. 2005

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A laser interferometer-deformograph with a 75-m-long arm has been developed by Moscow State University's Sternberg State Astronomical Institute to record and study lithospheric deformations over a wide frequency range. The design and the performance characteristics of the interferometer are described. It is located near Mount Elbrus, in one of the Russian regions with the highest level of geodynamical activity, which determines the range of geophysical and geodynamical problems to be solved using experimental data obtained with this instrument. Based on experience gained over ten years of routine observations, the whole measuring system has been comprehensively updated. As a result, its technical potentials have been substantially extended and the reliability and quality of experimental data have been improved. The limiting sensitivity of the laser interferometer is assessed, and the results from observations are presented.

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Section: The Second Hf (Seismic) Channelmentioning

confidence: 99%

Section: Laser Interferometer Sensitivitymentioning

confidence: 99%

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A Laser Interferometer-Deformograph for Monitoring the Crust Movement

et al. 2005

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“…The main concentration of effort is on strain instrumentation and preliminary work included the compilation of a survey of technique (Sydenham 1971) to assist formulation of the pro gramme which started seriously in 1970. A tensioned-wire strainmeter of improved design (see Sydenham 1969 a for a description of original units) is in operation, the results of a study made of progress with this new technique . Three other units, complete with calibrated electronic amplifiers and recorders, are in use on other projects.…”

Section: The Observatorymentioning

confidence: 99%

A Discussion on the measurement and interpretation of changes of strain in the Earth - Strain measurement in Australia with particular reference to the Cooney Observatory

Sydenham

1973

Phil. Trans. R. Soc. Lond. A

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A number of groups in Australia are concerned with Earth crustal movement measurement and interpretation. A brief description is given of their activities. Monitoring crustal movements requires methods of strain determination which have the best attainable precision and long-term stability. Paramount to improvement of the established techniques is need for a facility where the various methods can be compared in a reliable manner. The remainder of the paper describes the research programme of the Cooney Observatory (operated by the University of New England) which has a dominant theme of instrument development and verification. Rod, wire and laser strain-meters and the necessary peripheral equipment are described. Of interest is the continuing improvement of stable intermediate-length measuring bases in which a controlled temperature and pressure environment is created to eliminate the main systematic sources of instrument error during testing and calibration.

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“…No similar experiments appear to have been carried out on the strain field, probably because of the difficulty and expense of installing strain meters. We therefore decided to use several 10 metre wire strain meters (King et al 1969; to investigate the tidal strain variation in the vicinity of Queensbury Tunnel in Yorkshire. This site had originally been selected for strain measurements because the tunnel passes through weak coal measure deposits with shallow dips (Figs 1 and 2).…”

Section: Introductionmentioning

confidence: 99%

Inhomogeneous Tidal Strains in Queensbury Tunnel, Yorkshire

Bilham¹,

King²,

McKenzie³

1974

Geophys J Int

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Strain meters aligned along Queensbury Tunnel show amplitude variations of the diurnal tides of up to a factor of three, with smaller variations in phase. These observations are not easi!y explained because the semi-diurnal tides have different and smaller variations. The strain variations may be caused by local geological structures, but more observations and calculations are needed to test this hypothesis.

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New Strain Meters for Geophysics

Cited by 19 publications

References 4 publications

A Laser Interferometer-Deformograph for Monitoring the Crust Movement

A Laser Interferometer-Deformograph for Monitoring the Crust Movement

A Discussion on the measurement and interpretation of changes of strain in the Earth - Strain measurement in Australia with particular reference to the Cooney Observatory

Inhomogeneous Tidal Strains in Queensbury Tunnel, Yorkshire

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