A strainmeter is an instrument used by geophysicists to measure the deformation of the Earth. Linear strainmeters measure the changes in the distance between two points, using either a solid piece of material (over a short distance) or a laserinterferometer (over a long distance, up to several hundred meters).
Distortion seismometer
The type using a solid length standard was invented by Benioff in 1932, using an iron pipe; later instruments used rods made of fused quartz. Modern instruments of this type can make measurements of length changes over very small distances, and are commonly placed in boreholes to measure small changes in the diameter of the borehole. Another type of borehole instrument detects changes in a volume filled with fluid (such as silicone oil). The most common type is the dilatometer invented by Sacks and Evertson in the USA (patent 3,635,076); a design that uses specially shaped volumes to measure the strain tensor has been developed by Sakata in Japan.
All these types of strainmeters can measure deformation over frequencies from a few Hz to periods of days, months, and years. This allows them to measure signals at lower frequencies than can be detected with seismometers. Most strainmeter records show signals from the earth tides, and seismic waves from earthquakes. At longer periods, they can also record the gradual accumulation of stress (physics) caused by plate tectonics, the release of this stress in earthquakes, and rapid changes of stress following earthquakes.
The most extensive network of strainmeters is installed in Japan; it includes mostly quartz-bar instruments in tunnels and borehole strainmeters, with a few laser instruments. Starting in 2003 there has been a major effort (the Plate Boundary Observatory) to install many more strainmeters along the Pacific/North-America plate boundary in the United States. The aim is to install about 100 borehole strainmeters, primarily in Washington, Oregon and California, and five laser strainmeters, all in California.
strainmeter, strainmeter, instrument, used, geophysicists, measure, deformation, earth, linear, strainmeters, measure, changes, distance, between, points, using, either, solid, piece, material, over, short, distance, laser, interferometer, over, long, distance. A strainmeter is an instrument used by geophysicists to measure the deformation of the Earth Linear strainmeters measure the changes in the distance between two points using either a solid piece of material over a short distance or a laser interferometer over a long distance up to several hundred meters Distortion seismometerThe type using a solid length standard was invented by Benioff in 1932 using an iron pipe later instruments used rods made of fused quartz Modern instruments of this type can make measurements of length changes over very small distances and are commonly placed in boreholes to measure small changes in the diameter of the borehole Another type of borehole instrument detects changes in a volume filled with fluid such as silicone oil The most common type is the dilatometer invented by Sacks and Evertson in the USA patent 3 635 076 a design that uses specially shaped volumes to measure the strain tensor has been developed by Sakata in Japan All these types of strainmeters can measure deformation over frequencies from a few Hz to periods of days months and years This allows them to measure signals at lower frequencies than can be detected with seismometers Most strainmeter records show signals from the earth tides and seismic waves from earthquakes At longer periods they can also record the gradual accumulation of stress physics caused by plate tectonics the release of this stress in earthquakes and rapid changes of stress following earthquakes The most extensive network of strainmeters is installed in Japan it includes mostly quartz bar instruments in tunnels and borehole strainmeters with a few laser instruments Starting in 2003 there has been a major effort the Plate Boundary Observatory to install many more strainmeters along the Pacific North America plate boundary in the United States The aim is to install about 100 borehole strainmeters primarily in Washington Oregon and California and five laser strainmeters all in California See also EditDeformation monitoring Deformation physics Extensometer Infinitesimal strain theoryReferences EditAgnew DC 1986 Strainmeters and tiltmeters Reviews of Geophysics 24 3 579 624 doi 10 1029 RG024i003p00579 External links EditPinon Flat Observatory CA laser strainmeters GTSM Technologies AUS borehole strainmeters Plate Boundary Observatory Archived 2009 11 24 at the Wayback Machine US Geological Survey see under Fault Monitoring Archived 2010 04 12 at the Wayback Machine This geophysics related article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Strainmeter amp oldid 1147385969, wikipedia, wiki, book, books, library,
