莺歌海盆地断裂活动与地质灾害分析

Active faults and geological hazards in theYinggehai basin, the northwestern South China Sea

莺歌海盆地是南海西北部海域地质灾害类型较齐全的地区之一。根据野外调查资料,本文简要地分析了该区的活动断裂和地质灾害类型。区内活动断裂主要走向呈NW向,该方向的活动断裂主要有红河断裂带、中央拗陷东部断裂带和中央拗陷西部断裂带。红河断裂带在地震资料上显示为一倾向SW的正断层,表现为明显的重力梯级带和磁异常分界带,NE向断裂带分布于盆地中部,在重磁异常上表现为明显的异常带,在北部表现为被NW向的断裂切割。莺歌海盆地地质灾害类型主要有地震活动、泥底辟构造、滑坡与崩塌等。同时,还对该区地质灾害基本特征和分布规律进行了初步分析。

Yinggehai basin is one of the areas where almost all kinds of geo-hazards develop in the northwestern South China Sea. According to the information of the seismic data, the paper analyzes the basic characteristics and distribution regularity of the active faults in the Yinggehai basin. The Red River Fault Zone is a large slide and active fault zone. It controls the tectonic activities of the northwestern South China Sea and also controls the form and evolution of the Yinggehai basin. Up to the modern times the fault zone's activity becames weakness and took place 10 times M_s<5 earthquake. And at the same time, the geological hazard's characteristics and distribution of the area are discussed.