Results from a borehole optical fiber interferometer for recording Earth strain

Mark A. Zumberge; Scott DeWolf; Frank K. Wyatt; Duncan C. Agnew; Don Elliott; William Hatfield

doi:10.1117/12.2025896

20 May 2013 Results from a borehole optical fiber interferometer for recording Earth strain

Mark A. Zumberge, Scott DeWolf, Frank K. Wyatt, Duncan C. Agnew, Don Elliott, William Hatfield

Proceedings Volume 8794, Fifth European Workshop on Optical Fibre Sensors; 87940Q (2013) https://doi.org/10.1117/12.2025896
Event: Fifth European Workshop on Optical Fibre Sensors, 2013, Krakow, Poland

Abstract

We have installed a set of 250 m long borehole optical fiber strainmeters at Piñon Flat Observatory in southern California, USA. These instruments consist of an optical fiber stretched between two positions in the borehole – the upper position is at depth of 4 m and the lower is at a depth of 254 m. The tensioned optical fiber’s length is monitored interferometrically; vertical Earth strain is determined by recording the fiber length change over this interval. We achieve a strain sensitivity of about 0.01 n(epsilon) (10^–11) at periods near 1 s. The noise in the tidal band is 300 n(epsilon)/√Hz (near 1cycle per day). After an initial settling period of about a year, the instrument drift is 1-2 μ(epsilon) per year.

Citation Download Citation

Mark A. Zumberge, Scott DeWolf, Frank K. Wyatt, Duncan C. Agnew, Don Elliott, and William Hatfield "Results from a borehole optical fiber interferometer for recording Earth strain", Proc. SPIE 8794, Fifth European Workshop on Optical Fibre Sensors, 87940Q (20 May 2013); https://doi.org/10.1117/12.2025896

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