构造运动与中国沿岸平原的地质灾害

中国海岸穿过构造沉降带和隆起带，沉降带及隆起带断陷盆地的持续下降吸引了源远流长的大河在此人海，而隆起带内入海的河流多为近源小河，从而引起河流泥沙沿岸分配的不均和海岸沉积物的差异。沉降带内每公里海岸线接受的沉积物是隆起带的数十倍，且以砂质沉积物为主．隆起带河流泥沙来量少．而且砂质沉积物占了压倒的优势．河流泥沙沿岸分配的不均决定了中国沙质和淤泥质海岸的基本类型和分布格局、沉降带和隆起带松散沉积层的厚度和结构，山此产生了中国沿岸与第四纪沉积层有关的灾害和环境问题的有规律的分布。地面沉降主要分布于沉降带内，而地下海水入侵多出现在依赖地下水的隆起带内，底辟构造、浅层天然气往往在大河三角洲构成灾害和潜在的地质灾害．沉降带和隆起带断陷盆地内的海岸低地通常是海平面上升的主要脆弱地区．此外，丰富的河流泥沙使中国海岸对全球海平面上升的响应也不相同，如海岸湿地的再生和海岸侵蚀原因的复杂性等．

Tectonic activity and geological hazards in coastal plain zones of China

Tectonic activity in Chinese coastal zone controls uneven distribution of river-borne sediments which in turn leads to form wide strand-plains with thick fine-grained Quaternary strata in the subsidence belts and narrow strand-plains with thin coarse-grained Quaternary strata in the uplift belts. This results in main differences in Chinese coastal zones: sandy and muddy coast distribution and controls distribution of various environmental phenomena related to Quaternary stratigraphy, such as ground subsidence, subsurface salt-water intrusion. Ground subsidence basically occurs in northern Chinese coastal zone and storm surge caused by tropical cyclone strongly influences southern Chinese coastal zone. Relative sea-level rise, comprehensively considering the factors of global sea-level rise, tectonic subsidence, ground subsidence and trend rise of river level, is more important for local vulnerability assessment comparing with global sea-level rise. Superimposition of climatic extreme events on rising sea level creates serious economic loss and people casualty which is present every year in Chinese coastal zone, although dykes have been constructed along Chinese coasts. Coastal erosion is a serious environmental problem in Chinese coastal zone during last decades, but it mainly results from a deficit of sediments, owing to natural or anthropogenic factors. However, around Chinese large delta areas where fine-grained river-borne sediments are abundant, wetland still tends to be renewing. With building of large reservoirs on main rivers, water discharge and suspended load must be reduced, thus, coastal erosion would be accelerated and wetland renewing would be decelerated, and vulnerability of Chinese coastal zone would be exacerbated.