Fibre Optics as An Earthquake Sensor

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ETH experts in earth sciences and engineering geology have tested out a new method on the Rhone glacier that will allow detailed examination of the interior of the glacier and its movement.

ETH experts in earth sciences and engineering geology have tested out a new method on the Rhone glacier that will allow detailed examination of the interior of the glacier and its movement. The effectiveness of this new technique was better than expected.

Sometimes scientists simply need to try out something that no one has ever attempted before. ETH Professor Andreas Fichtner from the Institute for Geophysics decided to take a shot in the dark. Last week he and his colleague Fabian Walter from ETH Zurich’s Laboratory of Hydraulics, Hydrology and Glaciology, along with their doctoral students, conducted their first field tests on the Rhone glacier using a fibre-optic cable. Their goal is to be able in future to examine glaciers and draw conclusions about their internal composition, volume and movements.

Fibre-optic cables can be used to measure vibrations by directing short laser pulses into the cable. Minute impurities along the cable disperse the laser beam in a specific manner. If there is no change in the cable, the dispersion signal remains the same. If it expands in response to seismic activity, the dispersion signal is modified.

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Photo: A true expedition: researchers' base camp on the Rhone glacier. (CREDITS: Institute of Geophysics / VAW / ETH Zurich)