Assessment of Submarine Landslide Susceptibility in the Sea Area of Zhoushan

Abstract

The research on the submarine landslide susceptibility has important guiding significance for the site selection and construction of marine engineering. The Zhoushan Archipelago New Area is dominated by the marine industry, and the marine engineering under its jurisdiction is densely covered. This research selected the surrounding sea area of Zhoushan island as the study area to evaluate submarine landslide susceptibility. The factors such as seismic peak acceleration, proximity to fault zone, average wave height, slope and sediment types were selected to construct the evaluation index system, all of which were considered to be influential in the occurrence of landslides. Meanwhile, the AHP method was used to calculate the weight of each index factor. In combination with geographical information system, the study area has been classified into five classes of relative landslide susceptibility, namely, extremely low, low, medium, medium-high and high. The research result showed that: (1) The high susceptibility zone in the evaluation result was consistent with the position of historical landslide. (2) The five classes in the result of submarine landslide susceptibility assessment for study area accounted for 1.17%, 1.97%, 9.08%, 56.05% and 31.74% of the total area from high to low, and the area with susceptibility above middle grade mainly distributed in the underwater bank slope around the islands or the slopes position of the tidal current scours. (3) This research was a preliminary study on the susceptibility assessment of regional submarine landslides. It was limited by the availability of evaluation index data and submarine landslide data accumulation in the region. Besides that, the evaluation model was influenced by experience greatly, so the evaluation result had certain subjectivity.