GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.2 ___ GNGTS 2023 These events were interpreted as shallow icequakes and rockquakes related to the modifications in the rock glacier internal conditions during the warm months. By contrast, when a significant snow cover was present on site during winter months (Fig. 2b), recurrent microseismic events were depicted at higher frequencies (orange in Fig. 2f), likely related to snow and material compaction and stress modifications within the rock glacier due to increased load. A last cluster of events (yellow in Fig. 2f) showed very short duration and variable peak frequency over time. Their temporal evolution was however found to be very similar to the quakes of the purple cluster, suggesting a similar genesis. Conclusions Ambient seismic noise and microseismicity analyses provided useful hints to analyze the internal processes of rock glaciers at both daily and seasonal scales. The results of the different processing methods are in agreement in showing a rapid reaction of the rock glacier to temperature and precipitation modifications. The continuous passive seismic monitoring of the rock glacier can also be used as an early warning tool to identify possible melting-related natural hazards for the site. Fig. 1. (a) Geographic location of the study site. (b) Aerial picture of the site. The perimeter of Gran Sometta Rock Glacier is highlighted in blue. The red triangles display the location of the passive seismic network, the green square, close to Goillet Lake, indicates the location of the closest meteorological station. (c) Zoom on (b) with location of the four passive seismic stations.