Types and characteristics of potential geohazards in the sea area near Nanpu-Caofeidian,Hebei Province

Based on the geological and geophysical data,including shallow stratigraphic profiles,multibeam and single-beam bathymetric data,and sidescan sonar photographs,the potential geohazards in the sea area near Nanpu-Caofeidian,Hebei Province were analysed and classified,the geohazard map and geomorphologic map of the study area are compiled,and studied the spatial distribution characteristics of the geohazards which are closely related to marine engineering,such as shallow gas,active sand waves,seafloor erosion,active fault,buried cross-bedded sand layers,steep slopes,steep scarps and grooves,are examined. The shallow gas,steep slopes and scarps are usually developed near the boundary between the gentle erosive-accumulative nearshore slope and steep erosive nearshore slope. Large-scales grooves and seafloor erosion are usually distributed in erosive shelf depression. In the other parts of the study area,geohazard types are less discovered,while active sand waves and buried cross-bedded sand layers are local found in the shelf area.