Advances in Avalanche Monitoring in Norway: Insights from Distributed Acoustic Sensing

Snow avalanches pose significant risks in mountainous regions. Traditional detection methods often lack the precision and timely responsiveness crucial for effective risk management. This study introduces an innovative approach using Distributed Acoustic Sensing (DAS) to detect snow avalanches in Norway. The monitoring site is located along a road in Holmbuktura in northern Norway, close to Tromsø. The cable path is composed of two segments: In segment one (0 – 850 m) an existing telecommunication cable is used, while for segment two (850 - 1450 m) a new cable was installed. The pilot road was frequently impacted by avalanches. Over three winters, the system captured both avalanche occurrences and anthropogenic noises (e.g., vehicles, wind, sea waves, etc.). 

The area is monitored with an OptoDAS interrogator with a sampling frequency of 500Hz and 10m gauge length. A 5m channel spacing results in 270 virtual channels along the monitored road stretch. Our automatic detection process distinguishes is based on classical signal processing techniques. We can confidently detect avalanches that hit road level, and additionally determine snow deposit on the road. Furthermore vehicles are detected with exact location and speed, which is used to alert emergency units in case of trapped vehicles. In this project, the focus of the installation is to detect avalanches that hit the road and determine whether any vehicles were trapped under the avalanches. For the winter season of 2022-2023 eight avalanches hit the road. The DAS-based monitoring system managed to successfully detect and classify these avalanches.

Compared to conventional methods like radar, infrared, and camera-based systems DAS offers distinct advantages in avalanche monitoring. DAS excels in providing real-time, continuous monitoring with high sensitivity and precision over extensive areas, unaffected by visual obstructions and less impacted by adverse weather conditions. Its robustness and low maintenance needs stand out, particularly when compared to radar systems' high installation costs and limited area coverage, camera's susceptibility to weather/light conditions.

The application of DAS technology offers a promising avenue for real-time, accurate avalanche detection, potentially enhancing safety measures in high-risk areas. Furthermore, this concept, when fully operational, could detect the risk of collision between avalanches and vehicles and alert authorities in real-time, which would be crucial for time-sensitive rescue operations.