uantification of natural disaster is a new research area between the earth science, engineering science and the socio-economical science. The urbanization is an worldwide trend. This trend is especially pronounced in the countries of the Third World, where the number of cities over a million inhabitants has increases sixfold in the past 50 years. City people are more dependent on the infrastructure, i.e. the supply of water, electricity, gas, heating, telecommunications and transport connections than the more selfreliant rural population, which is more accustomed to helping one another in emergencies. Numerous natural catastrophes of recent years have shown quite emphatically how vulnerable the infrastructures of major cities are to minor breakdowns and how acute shortages in supply can develop within a short time. Our statistics showed that there is a empirical relation between the economic loss caused by natural hazards (in million US$) and the social wealth expressed by GDP²(in million US$) is:
Loss cause by natural hazards=a+b GDP+c GDP^2, where a, b and c are positive constants, it means that the losses increase faster than the increase of GDP. 