Tsunami Hazards Along the Chinese Coast from Potential Earthquakes

The recent Indonesian earthquake has awakened great concerns about destructive hazards along the Chinese coast. Scientists have provided a clear record of past tsunamis along East China that clearly indicate the potential for future tsunami damage to China. In this work we will assess from analyzing the probability for tsunami waves to hit the Chinese coast in the next century from large earthquakes coming from the neighboring subducting plate boundaries. This analysis is important because of the sharp increase in coastal population density in China, the intense development of harbors and the exploitation of mineral resources in coastal areas, ranging from Xiamen in the north to Hainan in the south. The probability seismic studies for the South China Sea and adjacent field were based on the relationship of Gutenberg- Richter (G-R) relationship between the number of local earthquake and magnitude. We studied the earthquakes of the global subduction belt. We found the earthquakes of the global subduction belt follow the G-R relationship. The plate boundary model came from P. Bird (2002). According to the historical earthquakes of South China Sea and adjacent field (From NEIC), and the tectonic and focal mechanism (HCMT), the studied field is divided two partitions. The latitude of the first partition is N (12-19 deg.); the second is N(19-23 deg.). There are twelve large earthquakes in the two partitions. Their magnitudes are bigger than 6. The probabilities of earthquakes in the South China Sea are computed by the local G-R relationship. They would determine the seismically-induced tsunami probability. In our study the linear shallow water equation is used for integrating the twelve earthquake induced tsunamis. The numerical scheme for the linear equations is the staggered leap-frog method. The code has been provided by Dr. Fumihiko Imamura, Tokohu University, Japan. We combined the probability of three segments of wave height, 2.0 to 1.0 meter, 1.0 to 0.5 meters, the wave height smaller 0.5 meters, in the tsunami modeling. We forecast that there is 3 percent probability for a ten foot tsunami wave to hit Hong Kong and Macau within the next 100 years.