Reconstruction of the Wenchuan debris flow process in August, 2022 by in-situ monitoring and analysis of seismic signals

Rainfall-induced debris flows are highly destructive due to their abrupt onset, rapid movement, and high sediment transport capacity, all of which can lead to significant loss of life and damage to infrastructure. However, a comprehensive analysis of their dynamic evolution remains limited by the scarcity of in-situ monitoring data. In this study, we utilized near-field seismic data recorded by acquisition instruments deployed in Wenchuan, China, combined with images and post-event field investigations to reconstruct the second debris flow event in Fotangba Gully. Seismic signal attenuation was compensated, and time-frequency analysis and power spectral density (PSD) calculations were conducted. The results reveal pronounced differences in signal amplitude and frequency content across stations, reflecting spatial heterogeneity in flow dynamics. We identified flow velocity and grain concentration as the dominant factors affecting the PSD curves. This research provides a framework for extracting debris flow kinematic characteristics from seismic signals and offers new insights for hazard evaluation and the design of mitigation strategies.