Natural Hazards and Earth System Science www.nat-hazards-earth-syst-sci.net 1561-8633 1684-9981 10 2 2010 10.5194/nhess-10-191-2010 http://www.nat-hazards-earth-syst-sci.net/10/191/2010/ http://www.nat-hazards-earth-syst-sci.net/10/191/2010/nhess-10-191-2010.html http://www.nat-hazards-earth-syst-sci.net/10/191/2010/nhess-10-191-2010.pdf 191 201 2010-02-02 Rockslide deformation monitoring with fiber optic strain sensors J. R. Moore jeffrey.moore@erdw.ethz.ch V. Gischig E. Button S. Loew Geological Institute, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland With micro-strain resolution and the capability to sample at rates of 100 Hz and higher, fiber optic (FO) strain sensors offer exciting new possibilities for in-situ landslide monitoring. Here we describe a new FO monitoring system based on long-gauge fiber Bragg grating sensors installed at the Randa Rockslide Laboratory in southern Switzerland. The new FO monitoring system can detect sub-micrometer scale deformations in both triggered-dynamic and continuous measurements. Two types of sensors have been installed: (1) fully embedded borehole sensors and (2) surface extensometers. Dynamic measurements are triggered by sensor deformation and recorded at 100 Hz, while continuous data are logged every 5 min. Deformation time series for all sensors show displacements consistent with previous monitoring. Accelerated shortening following installation of the borehole sensors is likely related to long-term shrinkage of the grout. A number of transient signals have been observed, which in some cases were large enough to trigger rapid sampling. The combination of short- and long-term observation offers new insight into the deformation process. 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