PROBABILISTIC CALIBRATION OF BASIC INTENSUTY FOR PARTS OF CHINA

Based on the results of seismic hazard analyses for 45 cities and towns in the Northern, North-western and South-western Regions of China, preliminary probabilistic calibration of Basic Intensity, as predicted by the Chinese Intensity Zoning Map, has been carried out. It is discovered that the Basic Intensity offered by the Zoning Map is roughly equivalent to an average intensity level with exceeding probability of 0.14 in 50 years.The calculation in this paper have been done in accordance with the common procedures of hazard analysis. Some main points that should be considered in practical application are as follows: 1) Reasonable estimation of the location and extent of potential seismic sources by both geotectonis structure and distribution of historical epicenters; 2) Estimation of the magnitude-recurrence relationships consistent with current level of seismicity; 3) Choice and use of the proper intensity attenuation laws, which reflect specific geotectonic structures of different regions.The results obtained from hazard analysis are discussed graphically and tabularly.