A Note on Numerical Evaluation of Tsunami Threats by Simple Hydrodynamic and Stochastic Models Referring to Historical Descriptions

Abstract

This work is a speculative study to clarify what is essential for hydrodynamic or stochastic studies of the tsunamis and what are important in the historical descriptions and the tsunami catalogs for numerical simulation and prediction and for stochastic evaluation of practical tsunami protection works. First, a brief description of the historical documents of past tsunamis are introduced and evaluated in order to give a local chronological tsunami catalog which will aid in understanding what should be remarked at reading the tsunami descriptions. Next to the descriptive tsunamis, numerical simulation of the past tsunamis were reviewed and evaluated. The author's finite difference method with a uniform grid spacing is introduced in order to show an agreable result as a simulation of a tsunami. The author has used a uniform grid spacing in his numerical model because he knows that it is helpful in minimizing the truncation error in a numerical model of a finite difference method. In any numerical simulation case, the historical descriptions are the essential references to confirm how successful the simulation is. Although, no numerical model can predict when the next tsunami occurs. The stochastic model is now very useful in making probabilistic prediction. This measure is for long-term practical planning of tsunami protection works with reliable references selected out of the historical documents of the past tsunamis and the tsunami catalogs well revised.