image of a tiltmeter



GEOXTM created the world's largest, deepest network of underground fiber-optic strain and temperature sensors and tiltmeters to measure the movement and deformation of rock systems underground.

The multidisciplinary and multi-institutional collaboration is led by geologist Herb Wang of the University of Wisconsin. Wang's colleagues include geoscientists, engineers and technicians from throughout the world. GEOXTM is sponsored by the Geomechanics Program of the National Science Foundation.

The first tiltmeters of the "Hydrostatic Level System" were installed in January 2009 to establish baseline measurements. Tiltmeters are sophisticated, highly sensitive instruments, but the operate on the same principle used in simple bubble levels. That is, water seeks a level. The tiltmeters installed in 2009 were the same type developed by Jim Volk for the Tevatron particle accelerator at Fermi National Accelerator Laboratory. GEOXTM arrays at the Sanford Lab include instruments on the 2000, 4100 and 4850 levels.

The GEOXTM research team also is developing a new method for measuring deformation and temperature changes in rock. The devices are called FROSTS (Fiber optically instrumented ROck Strain and Temperature Strips). Each consists of a 6-foot-long strip of stainless steel with fiber-optic strain and temperature sensors attached at 1-foot intervals. The FROSTS are grouted into boreholes drilled into the rock. Strain and temperature are measured using a laser light signal sent down the fiber optic cable to sensors.