The Dissemination Research And Identification Of Tsunami In Sea Continental Shelf Of East China

The tsunami generated by earthquake is a kind of sea wave directly created by the ocean floor uplifting and subsiding, which usually has great destructive power and could bring huge calamity to human. So, the tsunami research is an important project in the human disaster precaution field, especially important in tsunami discrimination and sea-quake disaster evaluation.Chinese scholars carried out research work in this field mainly after the 2004 tsunami in Indonesia,because in South China Sea, the possibility of seismic tsunami is great, it has become a hot study area in China scholars. However, the East China Sea coastal area is the most economically developed and most densely populated areas, it is still a lack of precise numerical simulation of the tsunami, once the tsunami hit this area, the consequences would be unthinkable. Therefore, it is necessary to study the characteristics of the potential tsunami in this area, this work is significance to the identification of tsunami and disaster assessment.The East China Sea region was studied in this thesis, firstly, the existence of the occuring possibility of earthquake and tsunami in the East China Sea was demonstrated from the aspects of the geological background of the terrain, the history of seismic activity and tsunami spatial and temporal distribution characteristics, also the Okinawa Trough is recognized as a potential source area, secondly, divided into two direction, the identification and spread of the tsunami were studied respectively.On the one hand, using numerical simulation methods, assuming five focal points in the Okinawa Trough, according to the six parameters which gave by Steven's tsunami experience seismic parameters in 6.0 - 9.0 magnitude earthquake as the initial conditions, Totally 30 earthquake Example were calculated , the tsunami dissemination process in the East China Sea was analyzed, particularly the possible tsunami disaster hit the coastal areas of Shanghai was studied in more details.The results showed: at the different focal point with the same magnitude, the initial tsunami wave height is the same; the earthquake cases which magnitude is less than 8.0 almost no impact on Shanghai, Example of 8.0 earthquake, only the focal point at the northern end has obviously impact on Shanghai; almost all The earthquakes with the magnitude of 8.5 and 9.0 have great influence to the coastal areas of Shanghai, especially in the northern section of the Okinawa Trough, Example of 9.0 earthquake possibly cause damage in part areas of Shanghai along the coast, the largest wave height might up to 3.9 meters. On the other hand, according to the characteristics of situation analysis and combining the water level changes which recorded by tsunami instrument, whether the tsunami disaster will happen was estimated. Tide is the major factor which influence on the change of daily water lever monitoring, the numerical simulation methods were used for tidal prediction at the monitoring points in this paper, measured with the real information, the results is quite well. Combined with the northern end point of the Okinawa Trough 8.5 earthquake and one day of the tidal prediction results, the theoretical value of water level at monitoring points of the different times after the earthquake and tsunami happened were given.Through the above-mentioned results show that: The East China Sea has the happening possibility of earthquake and tsunami; the Okinawa Trough is a potential source areas, as the impact to Shanghai area, the northern section of trough is greater than the southern section; and the laid monitoring points of Shanghai Seismological Bureau can timely and accurately identify the tsunami disaster.