Seismic signatures of large river dynamics revealed by a dense seismic array at the Tiger Leaping Gorge of the Jinsha River, SE Tibet

Fluvial seismology is an emerging field that exploits seismic signals generated by fluvial processes to monitor bedload transport and flow turbulence. Currently, most previous studies have focused on small mountain rivers, while seismic signatures from large rivers remain poorly explored. The Tiger Leaping Gorge is a deeply incised, narrow gorge in the upper Yangtze River characterized by extreme topographic relief and intense fluvial incision. Over a river length of approximately 20 km, the riverbed elevation drops by ~200 m, and the maximum discharge can reach ~5000 m³ s⁻¹, making the gorge an exceptional natural laboratory for investigating the coupling between seismic signals and hydrodynamic processes in large rivers. Until March 2022, we deployed 35 seismic stations along the riverbanks of the Tiger Leaping Gorge to continuously monitor the actively incising river segment.

We analyzed eight months of continuous seismic data along the river channel. In contrast to observations from small rivers, we identify two distinct and well-separated seismic energy bands at most stations. Temporal variations in both frequency bands show strong correlations with river discharge. We interpret the higher-frequency energy band as being primarily generated by small-scale eddy interacting with a rough riverbed, a process that appears to be particularly pronounced in large rivers. Building on existing models of turbulence-generated and bedload-generated seismic signals, we further tested different inversion approaches and applied them to all stations in the array. This allowed us to reconstruct the spatiotemporal variations in river stage and bedload transport across the study area.

Our results reveal that large rivers exhibit seismic signal characteristics controlled by distinct flow-related mechanisms, a phenomenon that has not been fully recognized in previous studies of small-scale rivers. Moreover, this study demonstrates that dense seismic arrays can resolve river dynamic processes at high spatial and temporal resolution, highlighting the potential of fluvial seismology for monitoring large river systems.