Abstract: The strait channels are densely covered in the sea area of Zhoushan Islands, and the instability of the slopes of the strait channels is generally developed and varied in scale. The frequent subaqueous landslides pose a greater threat to coastal engineering facilities such as submarine cables and port terminals. In December 2012, the sub-bottom profiles were detected in the sea area of Liuheng Island. Three main acoustic reflection interfaces and four formation units were divided, and the upper three formations were Holocene sedimentary layers. Six subaqueous landslides were found, which were scattered along the coast of Liuheng Island or adjacent to the strait channel slope. The landslides structure were whole landslide, and some of them were multi-step. From the scale of the subaqueous landslides, the volumes were between 1.6×10⁵ to 2.7×10⁷ m³, with 2 super-large landslides, 3 large landslides and 1 medium landslide. According to the correlation between the interface and the landslide body, it was speculated that the subaqueous landslides occurred in the late Holocene since 2.5 ka.

Key words: Liuheng Island, strait channels, shallow stratum structure, subaqueous landslides