The Study On The Characteristics Of Geo-hazard Factors In Qingdao Offshore

With the development of the marine exploitation and the increase of marineengineering, marine disasters are becoming a big threat to the environment we rely on, lifeand property. Qingdao city located in the east central part coast of China, with thedevelopment of marine engineering, the research of the marine disaster become more andmore important. Qingdao’s offshore area is complicated in geological environment, so filledwith the factors cause the geological multi-distater. Due to it is a economically developedarea, have already existed a large number of marine engineering’s construction. So to do theresearch in geological disaster of coastal belt in this area is very important in theory andpractice.With the support of the project1:250000geology survey in ocean area of Qingdao,this essay use the data attain from the project such as3000km of high resolution shallowseismic,1100km of scan sonar,1800km of single-channel seismic and water depth allcomes from Qingdao Institute of Marine Geology which is recently tested from Qingdaooffshore, and we also collected and filed many historical geological material, andrespectively investigated in submarine geomorphy, active fault, buried paleochannel,irruglar surface of the bed rock of the distribution of the characteristic and control factor,and found several aspects of potential geological disaster of characteristic factors inQeingdao’s offshore.Based on the data of single-channel seismic, there is an active fault on the west ofQianliyan near Qingdao offshore which is mainly in NE. We speculate that the active faultis based on the old fault or induced by the old active fault.By analyzing the data of high resolution shallow seismic and single-channel seismic,buried paleo-channels are seen in Holocene and middle Pleistocene.Three major buriedpaleo-channels which formed during Holocene distribute in the sea offshore near RushanBay, T-shaped Bay, Aoshan Bay and Laoshan. The channels formed during middlePleistocene divided into two branches in NE-SE direction, which distributed in the easternpart of Laoshan.The shallow gas is very shallow in vertical distribution whose top bound is about10mfrom the seabed and spread mostly in five parks which are in the same formation. Because the shallow gas located in the area around paleo-channels in the T-shaped Bay which are inthe same formation with the sediment of paleo-channels, we deduce that organic matters ofsediment from the land in paleo-channels lead to the formation of shallow gas through thebiodegradation.Shallow buried irregular bedrock mainly concentrates on six parks: T-shaped Bayhereabout, Qianliyan hereabout, the eastern and southern of Laoshan, south islandhereabout and the mouth of Jiaozhou Bay and Hongdao hereabout. Overall, the irregularbedrock mainly distributed in inshore areas and nearby island.The tidal sand ridges located in the mouth of Jiaozhou Bay and the SW of Laoshan instudy area. The tidal sand ridges near the mouth of Jiaozhou Bay extend in N-S. Erosionchannels are divided by the sand ridge and formed rid-furrow terrain.Erosion channels are located in the mouth of Jiaozhou Bay and Aoshan Bay and thesouthern of Laoshan Mountain by analyzing the images of side scan sonar.There are3subaqueous delta, Dagu River-Yang River delta, T-shaped Bay river mouthdelta and Rushan Bay river mouth delta.The main factors that influence the distribution of geological hazardous factors areneoteetonics, sea level changes and sedimentary dynamics. As the geological hazardousfactors are harmful to engineering, considerations should be taken into before constructionsin coastal zone.