地震带划分方案对地震活动性参数的影响

Effects of seismic belt division scheme on seismicity parameters

  • 摘要: 根据四川及邻区的地震构造背景、地震活动特征等,相对于《中国地震动参数区划图(2001)》采用的大尺度地震带划分方案(ldquo;大带方案rdquo;),在较小尺度上划分出了川滇块体地震带、甘南川北地震带、四川盆地地震带(ldquo;小带方案rdquo;).采用相同的原则和方法,分别统计得出了ldquo;大带方案rdquo;、ldquo;小带方案rdquo;的地震活动性参数.对比分析表明,在同一地区,不同的地震带划分方案将得到代表不同地震活动水平的地震活动性参数.大尺度地震带划分方案很可能低估高震级档地震的年发生率.采用小尺度的地震带划分方案,可以更加真实地反映区域的地震活动的水平,较好体现控制建筑物抗倒塌的地震作用的水平,有利于编制更为真实、安全的抗倒塌区划图.

     

    Abstract: 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.

     

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