Marine Geological Disaster Factors In Beibu Gulf Inshore Of Guangxi Province

The pan-beibu gulf rim economic circle is a key area in the development of southwes-tern China. During marine economic development, safety is an important issue in offshore engineering and construction. Therefore, marine geological disasters, as one kind of natural disasters, have got more and more concerns.This dissertation studied the marine geological disasters in near shore area of Guangxi, Beibu Gulf based on the projects of"Marine Geo-environment and Geo-hazard survey in nearshore area of Guangxi, Beibu gulf".Up to now, there is no unified criterion to classify the types of marine geo-hazards. The criterion initiated by Feng et al. was suitable for marine geo-hazards lassification in Beibu Gulf. In that criterion the marine geo-hazards were divided into two groups: active geo-hazards and non-active restrictive geological conditions.The results demonstrated that in study area the active geo-hazards included fault, shallow gas(pockmark), sand wave and earthquake. While on-active restrictive geological conditions consisted of buried channel, irregular bedrock surface, groove, concavo-convex and beach. The distribution, formation and dangers for various types of marine geological disasters were also analyzed.Shallow geophysical methods were utilized to detect active faults in offshore marine areas. The results proved that the methods had good effect in study of active faults such as shape, position and configuration. Ideal detection effects have been obtained through new data processing technology for complex interference factors in study area.Nanliu River is the largest river in Guangxi coastal region. Its buried paleo-channel was revealed by survey information using geophysical detection and sea floor sampling. The extend scope and direction of paleo-channel was restricted by faults'directions. The paleo-channels, which were formed at the low sea level during late Pleistocene to early Holocene, were mainly belongs to unsymmetrical type. They have important significance on paleo-environment recognition, offshore construction and disaster prevention and mitigation.