| 05 Jun 2026
Method for near real-time detection of snow avalanches using Distributed Acoustic Sensing
Abstract. We present a novel method for near real-time snow avalanche detection using Distributed Acoustic Sensing (DAS). A ∼10 km long telecommunication cable permanently installed along the avalanche-prone Flüelapass road (Swiss Alps) was continuously monitored over a full winter. Avalanches, including events that did not physically reach the cable, were clearly recorded and confirmed with photographic evidence. To discriminate avalanches from anthropogenic signals, we introduce a dual-frequency short-term over long-term average attribute that produces coherent high-value spatio-temporal signatures for avalanches, while vehicles predominantly generate negative values with pronounced move-out. The workflow consists of (1) a quasi-instantaneous threshold-based trigger to detect onset time and location, followed by (2) a rapid waterfall image analysis to estimate event extent and invalidate traffic-induced alerts. The first step issues alerts with millisecond-scale latency and meter-scale spatial resolution. The second step introduces additional latency, as it requires the event to sufficiently develop in order to assess its spatio-temporal morphology and confirm or discard the initial trigger. Our system issued alerts only 4.5 ‰ of the time when the road pass was open (i.e. 2.5 hours over 23 days), demonstrating the robustness against traffic, and 0.36 ‰ of the time when the pass was closed (i.e. 55 minutes over 108 days). Among those, a total of 73 potential avalanches were identified, most of them occurring during three independently documented avalanche episodes. These findings demonstrate that DAS represents a viable and cost-effective solution for operational real-time avalanche monitoring, with potential applicability to broader natural hazard detection.
Dear Editors and Authors,
I have read the manuscript, 'Method for near real-time detection of snow avalanches using Distributed Acoustic Sensing.' The study is very interesting and presents valuable findings, and the manuscript itself is clear and well-organized. The work represents a strong contribution to DAS-based avalanche monitoring, particularly because it addresses the important operational challenge of distinguishing avalanche signals from anthropogenic noise.
I have only a few comments and suggestions that may help clarify the methodological scope and communicate the results more effectively.
General comments
1) The proposed detector seems to work well with avalanches that exhibit weak or delayed low-frequency STA/LTA responses relative to their full-band responses. However, large avalanches or the avalanches that are very close to the cable may generate higher/faster low-frequency STA/LTA responses and thus lower HVR amplitudes. Such events could therefore be missed or potentially misclassified as moving anthropogenic sources. It would be useful for the authors to discuss this potential limitation and clarify whether events with strong simultaneous low- and high-frequency responses were observed in the dataset.
2) The (1/\sqrt{2}) term in Equation 2 is not sufficiently explained. In its current form, assuming both STA/LTA quantities fluctuate around one during stationary background noise, the resulting attribute does not appear to fluctuate around zero.
3) A discussion of false negatives would be valuable for understanding the limitations and operational applicability of the method. Were there independently observed avalanches that the system failed to detect?
4) It would be a nice add-on if the authors could discuss the seismo-acoustic pathways of avalanche signals, signal phases and limitations of DAS more explicitly.