地震危险性分析衰减不确定性校正中的主观不确定性

SUBJECTIVE UNCERTAINTIES OF ATTENUATION UNCERTAINTY CORRECTION IN SEISMIC RISK ANALYSIS

实际使用中的危险性分析模型均带有主观的性质,其与现实原型之间的差异包含两种性质不同的不确定性,即现实模型与理想模型之间的主观不确定性,和理想模型与现实原型之间的随机误差或客观不确定性。本文具体讨论对衰减规律作(客观)不确定性校正时主观不确定性的影响问题。文中分析了衰减不确定性校正的两种做法,即在危险性分析中直接校正和先忽略衰减不确定性,求得危险性曲线后总校正的做法,讨论了两者的等价性,并用半定量的方法指出影响校正因子的主要因素,即衰减公式的标准差。文中指出现行衰减不确定性校正中明显存在以下主观不确定性问题:使用等震线等效圆半径或等效椭圆长短轴建立烈度衰减规律必然低估标准差,从而低估地震危险性;以现行借用法得到的地震动参数衰减规律通常高估标准差,从而高估地震危险性。文中提出了修改借用法借用原则的建议。

All the practical seismic risk analysis models are of subjective nature, the difference between them and the real prototypes includes uncertainties of two kinds of different nature, namely, the random error between the practical model and the ideal model or the objective uncertainty. This paper will discuss the influence problem of the subjective uncertainty on the attenuations law when the uncertainty is objectively corrected. Two methods for correcting attenuation law of the earthquake motion obtained using the existing borrowing method usually overestimate the standard error, therefore, the seismic risk will be overestimated. The paper put forward the suggestion to modify the borrowing principle of the borrowing method.