Tsunami is one of the most serious disasters. To prevent from the loss, an effective warning system must be established. Nowadays, there is no warning system that is both accurate and fast enough to generate the warning in time, thus false alarms are common. Soon people will ignore the warning, and we may face another tragedy. There is a program named TUNAMI which can accurately calculate the water level and the speed of tidal wave given initial parameter, but this program is very slow due to a lot of calculation. The parallel tsunami simulation program will be the parallel version of TUNAMI, applying both functional and domain decompositions. This program will be much faster than the original program and will be able to be used in real-time warning system.