Seismo‐Acoustic Characterization and Array Processing of Dry‐ and Wet‐Snow Avalanches

Abstract Snow avalanches generate complex seismic and infrasound signals influenced by terrain, snow properties, flow regime, and avalanche size. In this controlled field study, we analyzed the seismo‐acoustic characteristics of three avalanches that released along the same path in the Dischma valley above Davos, Switzerland. The avalanches were recorded using co‐located seismic and infrasound arrays, minimizing confounding effects related to topography, wave propagation, and source–receiver geometry, enabling a direct comparison of signal characteristics and source parameters. We compared a dry‐snow and a wet‐snow avalanche of similar size, as well as a larger wet‐snow avalanche. A Doppler radar provided independent constraints on release times and flow location. By analyzing signal amplitudes, frequency content, and beamforming‐derived source parameters, we assessed how avalanche type and size influence seismo‐acoustic signals. Our results showed that avalanche size primarily controls seismic amplitudes, whereas the presence of a suspension layer governed infrasound strength. Notably, the large wet‐snow avalanche developed a suspension layer and generated strong infrasound amplitudes. Beamforming retrieved robust source parameters for all events. The infrasound data yielded stable backazimuths and slowness values even at low signal amplitudes, while the seismic data exhibited more complex wavefield patterns influenced by seismo‐acoustic coupling. Comparison with radar observations confirmed the accuracy of array‐based localization. Beamforming‐derived source parameters also provided earlier and clearer indications of avalanche motion than single‐sensor time series or spectrograms. Overall, our findings demonstrate that combined seismic and infrasound arrays provide complementary insights into avalanche processes and may support future developments in operational avalanche monitoring.