Abstract
—We have developed and operated optical fiber interferometers for monitoring displace ments within boreholes, as part of a program of crustal deformation measurement. These optical fiber strainmeters—a total of twelve instruments at two sites in southern California—were installed to sense the motion of the end-monuments of much longer baseline strainmeters and tiltmeters, allowing correction for any near-surface ground movement. One of the installations was specifically designed to investigate the distribution of deformation with depth, measuring over several borehole length-intervals from 5 m to 50 m. The displacements recorded over year-long time scales along these length intervals range up to 6 mm and show internal consistency and stability at the 50 μ m level. The use of these interferometers to provide correction signals for kilometer-scale crustal strain measurements has resulted in greatly improved records.
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Received May 27, 1997, accepted December 12, 1997.
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Zumberge, M., Wyatt, F. Optical Fiber Interferometers for Referencing Surface Benchmarks to Depth. Pure appl. geophys. 152, 221–246 (1998). https://doi.org/10.1007/s000240050152
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DOI: https://doi.org/10.1007/s000240050152