香港东南海域的断层分布及潜在地质灾害分析

Distribution of faults and Analysis for Geo hazard

香港东南海域，在水深６３ｍ区域内，基岩埋藏深度可达６００ｍ，晚第四纪沉积厚度１０－４８ｍ，由上而下可划分为Ａ１、Ａ２及Ａ３三个层组，Ａ１层厚６～１３ｍ，为浅海相粉砂质粘土及粘土质粉砂，１４Ｃ年代为９０００年以来的全新世沉积；Ａ２层厚０－２０ｍ，为河湖相粉砂质粘土及砂砾石沉积，底部有一侵蚀面；Ａ３层厚２～２０ｍ，为海陆交互相砂泥互层及砂砾沉积，与下伏地层间为不整合接触。在这一海区已发现多条活动断层，其中主要有４条，呈ＮＥＥ向及ＥＷ向分布，长１０～２０ｋｍ，位于海底以下４０～１２０ｍ，它们对晚第四纪沉积的分布有控制作用，并与地震活动有密切关系，说明南海北部近岸断裂带是本区潜在地质灾害的主导因素。即将开展的“珠海～深圳近岸海洋地质环境及地质灾害防治的调查研究”项目将为本区地质灾害防治和经济建设的持续发展提供更详细的基础资料。

Basement rock is buried up to 600m below seabottom in the southeast sea area out of Hong Kong The late Quaternary deposits in this area were about from 10 to 48m thick based on the geophysical data, and can be divided into three layer as A1,A2 and A3 An erosion exists between A2 and A3, but a discordant contact occurred below the A3 layer Through the survey, 4 important active faults were discovered below the seabottom from 40 to 120m and 10 20km long These faults dominated the distribution of the late Quaternary deposits along the same direction NEE or EW, and close related to earthquake In view of this, the near shore fault zone of the northern part of the South China sea was the primary Geo-hazard factor in this sea area