Research of Tide Influence on 2011 Japan Tsunami Wave in Eastern China Sea Area

Setting up numerical model is one of the most effective methods to study tsunami propagation process and its impact to the offshore area. Most of previous numerical models of tsunami are based on the static water level (mean sea level), neglecting influence of water level change with time and space on tsunami spread and waveform due to tide phenomenon. A 2-dimensional tide-tsunami couple model has been built to analyze the tide effect on 2011 Japan tsunami wave in eastern China sea area. Stimulation results show that changing amplitude of the maximum tsunami wave height is the most remarkable effect of tide, case of considering astronomical tide condition may bring more than +/- 50% wave height difference than the stimulation in mean sea level. The presence of tide also has a certain adjustment impact on the largest wave position in the tsunami wave train and its arrival time, but it is not as evident as that exerted on the variation of the maximum wave height. Compared with the formal two aspects, tide's influence on tsunami wave spread speed is the weakest which only lead to a variation within +/- 10%. Since different geographical locations of reference stations, tsunami wave spread routes vary from site to site, there is no consistent variation tendency of tsunami characteristics in above 3 aspects comparing 2 kinds of water level. Therefore, effect of tide should be considered in tsunami research and forecast as far as possible.