Elements, types, and risk zoning of marine geohazards in the sea area of the Qizhou Islands

ObjectiveThe sea area of the Qizhou Islands, located to the east of Hainan Island, is prone to frequent earthquakes due to the tectonic processes including active fault zones and the Hainan mantle plume. The southern part of the Qizhou Islands is close to the continental shelf break, with well-developed canyons and channels, making it prone to seabed instability and threatening the safety of engineering facilities in this area. However, research on marine geohazards in this sea area is scarce, and the development characteristics of geohazard elements remain unclear. Therefore, it is of great significance to conduct an in-depth study on marine geohazards for disaster prevention and mitigation in this area. MethodsIn this study, 2D seismic data were used to clarify the potential risks of marine geohazards in the sea area of Qizhou Islands. ResultsSix geohazard elements were identified in the sea area of the Qizhou Islands: Volcanoes, faults, shallow gas, mass transport deposits (MTDs), channels, and canyons. According to their quantity, scale, and distribution characteristics, the study area was divided into 12 blocks with three risk levels (low, medium and high risk). Based on the topographic, geomorphological, and tectonic activity characteristics of different blocks, targeted recommendations for the prevention and control of marine geohazards in the sea area of the Qizhou Islands are proposed. ConclusionThe research results provide a scientific basis for disaster prevention and mitigation as well as the construction of marine engineering facilities in the sea area of the Qizhou Islands.