晋冀蒙交界地区地震危险性评估及地震活动性分析

本文利用晋冀蒙交界地区1500年以来记录较完整的M_S5.0及以上历史地震烈度资料和2000年以来的地震活动资料,分别进行地震灾害危险性和地震活动性分析。首先,利用ArcGIS将历史地震烈度资料数字化,没有等震线记录的地震用烈度衰减关系计算烈度圈半径。将研究区划分成0.1°×0.1°的网格,将烈度资料分配到与之相交的每个网格,并用烈度-频度关系计算每个网格的烈度a、b值。基于地震发生遵从泊松分布的假定,估算未来50年内晋冀蒙交界区遭受某一地震烈度的超越概率。同时,计算50年超越概率10%对应的地震烈度,计算结果表明张家口蔚县、阳原和山西广灵县周边地区的地震危险性较高。最后,采用中小地震能量密度值计算方法,对2000年以来的现今地震活动进行定量分析,与历史地震烈度资料分析结果进行对比,发现中小地震活动圈定的危险区与历史地震烈度资料评估计算的概率高值区相对应,因此,这两种方法可为晋冀蒙交界地区的地震活动性和危险性评价提供参考。

Seismic Hazard Assessment and Seismic Activity Analysis of Shanxi-Hebei-Inner Mongolia Area

This paper analyzed the seismic hazard and activity in Shanxi-Hebei-Inner Mongolia area, based on the M_S5.0 earthquake intensity data since 1500 and the seismic activity data since 2000. These historical seismic intensity data were digitized with ArcGIS, and the radius of the intensity circle without isoseismic records were calculated with the earthquake intensity attenuation relation. The research area was divided into a grid of 0.1°×0.1°, the intensity data were distributed to each grid that intersects it, and the intensity values a and b of each grid were calculated by using the intensity and frequency relationship. Based on the assumption that earthquake occurred in accordance with the Poisson distribution, the probability of surpassing a certain seismic intensity in Shanxi-Hebei-Inner Mongolia area in the next 50 years was estimated. At the same time, the earthquake intensity corresponding to the probability of exceeding 10% in 50 years was calculated. The results show that the seismic hazard is higher in the surrounding areas of Yu County, Yangyuan in Zhangjiakou and Guangling County in Shanxi. The energy density values of moderate and small earthquakes since 2000 were calculated and compared with the analysis results of historical seismic intensity data. The results show that the dangerous area delineated by the moderate and small earthquakes activities corresponds to the high probability areas calculated by the assessment of historical seismic intensity data. Therefore, these two methods can provide a reference for the seismic activity and hazard assessment in Shanxi-Hebei-Inner Mongolia area.