Fiber optic sensors to improve landslide prediction

Detecting and monitoring both large landslides and slow slope movements could be a lot easier and cheaper with optical fiber sensors, says a study.

Distributed optical fiber sensors could be used as an entirely new tool to monitor areas subject to landslide risk and to develop early warning systems based on geo-indicators - early deformations - of slope failures, the findings showed.

This new technology can detect small shifts in soil slopes, and thus can detect the onset of landslides.

Usually, electrical sensors are used for monitoring landslides, but these sensors are easily damaged.

Optical fiber sensors are more robust, economical and sensitive, and this is where the new technology could make a difference, the researchers noted.

"Distributed optical fiber sensors can act as a "nervous system" of slopes by measuring the tensile strain of the soil they are embedded within," said Luigi Zeni, a professor at Second University of Naples in Italy.

The researchers worked out a way of combining several types of optical fiber sensors into a plastic tube that twists and moves under the forces of pre-failure strains.

Researchers were then able to monitor the movement and bending of the optical fiber remotely to determine if a landslide was imminent.

The use of novel fiber optic sensors "allows us to overcome some limitations of traditional inclinometers, because fiber-based ones have no moving parts and can withstand larger soil deformations," Zeni added.

The study will be presented at The Optical Society's (OSA) 98th Annual Meeting, Frontiers in Optics, being held Oct 19-23 in Tucson, Arizona, USA.