This study presents an innovative fiber-optic sensing system for monitoring debris flows. The system mainly comprises an interrogator and four fiber Bragg grating accelerometers. The field tests show that signal-to-noise-ratio (SNR) of the fiber-optic sensor is 10 dB higher than that of a geophone. Following confirmation of the reliability of the proposed sensing system, the systems are deployed along the Ai-Yu-Zi and Chu-Shui Creeks in Nautou County, Taiwan, for monitoring debris flows. The four accelerometers are installed in series. The systems have detected several debris flows in 2012. The monitored data reveal that the frequency range of the acceleration of ground vibration is 10-150 Hz, which is the same as that of the velocity of ground vibration detected by a sensing system that includes geophones. Because the fiber-optic sensing system is more sensitive than the geophone system, the proposed fiber-optic sensing system is highly promising for use in monitoring natural
disasters that generate ground vibrations.
Key Words : Fiber-optic sensing system, fiber Bragg grating, debris flow, ground vibration.