Abstract
Earthquake disaster is dependent upon both seismic intensity and strength of establishment. The higher the strength, buildings become more safe, which in turn increases the cost of investment. Therefore there exists an optimum strategy to minimize loss (=investment/life). The Monte Carlo simulation of construction and destruction of buildings is carried out by generating a time series of earthquake occurrence. The strength of buildings is expressed by the magnitude M and is assumed to decrease with time according to exponential decay law. Effects of partial damage and repair are included. It is concluded that the initial strength corresponding to M=7.5-8.5 is optimum. However, there exists no optimum solution if the effect of half damage is significant.
Economic merit of earthquake prediction and of counterplan is also studied. It is found that the merit is sensitively dependent upon a reliablity of prediction which is expressed by (damaged area/area where damage is predicted). If this ratio is 50, any counterplan appears to be of no use.
