Quantitative assessment of geological risks in the coastal waters from Huizhou to Shanwei, north of the South China Sea

Based on single-channel seismic interpretation, regional borehole data, and geological background information from the nearshore waters between Huizhou and Shanwei in the northern South China Sea, four main types of marine geological hazards were identified: faults, buried paleochannels, shallow gas, and shallow bedrock. Using the major regional geological hazard types as evaluation indicators, we determined the weight and membership degree of each indicator through the Analytic Hierarchy Process (AHP) and the normal distribution function, thereby establishing a geological hazard risk evaluation index system for nearshore marine areas. A fuzzy comprehensive evaluation model was subsequently constructed to quantitatively assess the hazard risk and seabed stability of the study area. The comprehensive evaluation results were visualized, and the region was classified into five levels of geological hazard risk. The assessment reliably captures the geological hazard characteristics and spatial distribution in the study area, providing practical guidance for site selection and risk avoidance in coastal engineering projects such as offshore wind farms, ports, and submarine pipelines. They also offer methodological reference for establishing a marine geological hazard risk evaluation system. The high-hazard zones identified in this study should be regarded as priority areas for detailed geotechnical investigation, engineering avoidance, and risk-informed coastal planning before major offshore construction.