Construction of Logic Trees and Hazard Curves for Probabilistic Tsunami Hazard Analysis

摘要

Due to the difficulties in forecasting the intensity and the source location of tsunami the countermeasures prepared based on the deterministic approach fail to work properly.Thus,there is an increasing demand of the tsunami hazard analyses that consider the uncertainties of tsunami behavior in probabilistic approach.In this paper a fundamental study is conducted to perform the probabilistic tsunami hazard analysis (PTHA) for the tsunamis that caused the disaster to the east coast of Korea.A logic tree approach is employed to consider the uncertainties of the initial free surface displacement and the tsunami height distribution along the coast.The branches of the logic tree are constructed by reflecting characteristics of tsunamis that have attacked the east coast of Korea.The computational time is nonlinearly increasing if the number of branches increases in the process of extracting the fractile curves.Thus,an improved method valid even for the case of a huge number of branches is proposed to save the computational time.The performance of the discrete weight distribution method proposed first in this study is compared with those of the conventional sorting method and the Monte Carlo method.The present method is comparable to the conventional methods in its accuracy,and is efficient in the sense of computational time when compared with the conventional sorting method.The Monte Carlo method,however,is more efficient than the other two methods if the number of branches and the number of fault segments increase significantly.