地震区划原则和方法的研究--以华北地区为例.
RESEARCH ON THE METHODOLOGY AND PRINCIPLE OF SEISMIC ZONATIONRESULTS OF THE TRIALS IN NORTHERN CHINA
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摘要: 本文基于对我国华北地区地震活动在时间和空间不均匀分布的认识,吸收了近20年来地震预测方面的科研成果,采用目前国际通用的地震危险性概率分析方法,通过对华北区划的试验,对地震区划的原则和方法提出了如下改进: 1.以地震带作为地震活动性参数的统计单元.引入地震活动趋势估计因素,评定表征地震活动水平的年平均发生率,以使区划结果同预测未来时间段地震活动水平相适应; 2.采用按震级挡次分配各潜在震源区的年平均发生率,可以合理地评估高震级地震的危险程度; 3.采用以震级挡次为条件概率的空间分布函数,刻画地震带内各潜在震源区之间发生相应震级挡次地震的相对危险程度,使区划结果更好地反映地震活动在时间和空间上不均匀性分布的特点; 4.在地震危险性分析计算中,引入了方向性函数项,使得分析模型更接近我国地震震源的实际情况.Abstract: Based on the cognizance of the temporal-spatial inhomogeneity of seismicity in Northern China, adopting the results of earthquake prediction in the past two decades and the currently used methods of seismic hazard analysis, and after some seismic zonation trials in Northern China, some improvements on the zonation principle and methodology were made:(1) Seismic zones were taken as statistic units where seismicity parameters were obtained. Tendency analysis was introduced. Earthquake annual average occurrence rates were estimated corresponding to the seismicity level in the future period;(2) Average annual earthquake occurrence rates for a given magnitude interval of a specific seismic zone were assigned to potential sources in the same zone considering the relative risk levels among these sources. Thus, the risk of great earthquakes can be estimated.(3) The probabilistic spatial distribution function under the condition of magnitude interval was suggested to reflect the temporal and spatial inhomogeneity of seismicity.(4) An orientation function in the seismic hazard analysis model was adopted, which reflects the real conditions of earthquake foci in China.