pure and applied geophysics

, Volume 152, Issue 2, pp 221–246

Optical Fiber Interferometers for Referencing Surface Benchmarks to Depth

  • M. A. Zumberge
  • F. K. Wyatt

DOI: 10.1007/s000240050152

Cite this article as:
Zumberge, M. & Wyatt, F. Pure appl. geophys. (1998) 152: 221. doi:10.1007/s000240050152

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.

Key words: Optical fibers, strainmeters, benchmarks.

Copyright information

© Birkhäuser Verlag Basel, 1998

Authors and Affiliations

  • M. A. Zumberge
    • 1
  • F. K. Wyatt
    • 1
  1. 1.Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0225, U.S.A. Phone: 619-534-3533. Fax: 619-534-9873.US