Effects of seismic belt division scheme on seismicity parameters

Abstract: Comparing with the large spatial scale seismic belt division scheme (large-belt scheme) adopted by Seismic Ground Motion Parameter Zonation Map of China, 2001, a small scale seismic belt division scheme (small-belt scheme) is worked out based on tectonic background and seismic activity in Sichuan and adjacent areas. The small-belt scheme includes Sichuan Yunnan block area belt (SYBAB), Southern Ganshu-Northern Sichuan belt (SGNSB) and Sichuan Basin belt (SBB). With the same deduction approach, the seismicity parameters are determined from the small-belt and large-belt scheme, respectively. Result of a comparison study indicates that, for a specific area, different division schemes result in different seismicity parameters, presenting different seismic activity levels. The large-belt scheme may underestimate annual occurrence rate of large earthquakes, while the small-belt scheme shows better performance in representing actual regional seismicity level and possible earthquake action for anti collapse design of buildings. The small-belt scheme would be more acceptable in compiling a feasible and safe anti collapse zonation map.