Tsunami hazards along Chinese coast from potential earthquakes in South China Sea

The pair of earthquakes off Taiwan on December 26, 2006 and the subsequent disruption of the Internet traffic have called attention to the potential destructive hazards along the Chinese coast from tsunamis. Historical records show past tsunami earthquakes in this region. Using GPS, earthquake focal mechanisms and geological evolution, we have delineated the dangerous zones in the Philippine Sea plate where major earthquakes may occur. The Manila Trench is identified as being most susceptible to future major earthquakes. We have obtained the local Gutenberg–Richter relationship for five sections along the Philippine Sea plate boundary and use this information for determining the probability distribution for tsunami waves of various heights to impinge on various Chinese cities. We devise a new method called the probabilistic forecast of tsunami hazard (PFTH), which determines this probability distribution by direct numerical simulation of the waves excited by hypothetical earthquakes in these zones. We have employed the linear shallow-water equations over the South China Sea. We have also compared them with results from the nonlinear version and found that the linear treatment serves our purpose sufficiently well. In the next century the probability of a wave with a height of over 2.0 m to hit near-coast ocean of Hong Kong and Macau is about 10%. Cities in Taiwan are less vulnerable than those on the mainland coast.