Revealing lakebed sedimentary history in Yigong Lake, Tibetan Plateau using distributed acoustic sensing

Yigong Lake, formed by a landslide in 1900, remained stable until a second landslide in 2000 breached the dam, causing significant economic losses and devastating downstream disasters. Located in the active convergence zone of Tibetan Plateau, the lake's shallow structure is crucial for assessing geohazards and advancing research on sedimentation and geodynamics. This study uses Distributed Acoustic Sensing (DAS) technique to image the lakebed sedimentary layers. By deploying fiber-optic cable, including 725 meters buried beneath the lakebed, we identified three layers: a uniform upper layer of unconsolidated sediments, a laterally thickening middle layer with variable compaction and deposition from multiple processes, and a deepest layer with relatively low velocities, compacted sediments reaching depths of 110 meters but not extending to bedrock. Forward modeling confirmed the accuracy of our results, providing valuable insights into landslide-dammed lake dynamics and hazard mitigation, while also demonstrating portable DAS’s reliability in remote, complex environments.