Approach for an Early Warning System for Debris Flow Based on Acoustic Signals

Abstract

Sediment-related hazards like debris flows, debris floods, and landslides are an ever-increasing threat to people and property, so the ability to detect debris flows as early as possible is an essential task to protect settlements and traffic routes. Past studies have shown that debris flows and debris floods emit a detectable signal in the infrasonic spectrum and induce characteristic seismic signals. Several approaches to detect debris flows with infrasonic or seismic sensors are already existing, but so far no warning system based on a combination of seismic and infrasound sensors has been considered. Previous studies have already presented that seismic and infrasonic signals of alpine mass movements are correlated and complementary and that the combination of these two sensor types can serve as basis for an error resistant warning system. So this work aims to build up a warning system for detecting debris flows by analyzing the seismic and infrasound waves. The developed system is build up on a minimum of one seismic and one infrasound sensor which are co-located and a microcontroller which runs a detection algorithm to detect debris flows with high accuracy in real time directly on-site. The detection algorithm is based on an analyses of the evolution in time of the frequency content of the mass movement signal and has been tested with debris flows and debris floods signals monitored at test sites at Lattenbach (Austria) and Illgraben (Switzerland). A first version of this new system is currently tested and evaluated at several test sites in Austria.