EXTREME GEO-DISASTERS AND RISKS

A concept of Extreme Geo-Disaster and Risk is proposed in this paper.Extreme geo-disasters are considered to be geo-events of most low probability in the earth recent evolution.However,low probability of natural event does not mean that it will happen only in the far future,and it does not exclude that such geo-disasters may happen in relatively near future within our or next generations.Strong earthquake Ms 8.0 on 12th May, 2008 in Wenchuan,China,which caused large amount of fatalities and structure damage,showed the typical characteristics of an extreme natural disaster.It once again rang a tocsin to warning human society.It is a question,if human would forget it,when it passed and the terrible situation changed.Therefore,the author appeals that engineering geologists have to pay attention to and deal with such extreme disasters and risks.Scientific recognition of the level of natural dynamic forces responsible for extreme disaster provides an essential basis in the disaster prediction,and this should be one of the essential objectives of engineering geology.Regional study of geo-sphere dynamic processes may help in aiming at this purpose.To assess the potential risk an approach of impact area estimation is important and further analysis of relationship between the damaging effect and vulnerability damaged objects gives an assessed level of disaster risk.In the strategy of risk management a kind of precaution measure and warning should be focused instead of merely engineering protection.Social awareness and preparedness are equally important in the extreme risk mitigation.Accordingly a series of strategic measures may be worked out for the disaster reduction,which are different from that of normal safety design standard and mainly consist of non-engineering measures.In the progress of science and technology the human capability in reduction and management of extreme natural disaster should be much updated in the near future.