上海及邻近地区地震烈度衰减规律研究

上海市是国际性大都市,确定合理的抗震设防标准,对于城市防震减灾、经济建设和社会可持续发展具有重要意义。地震动衰减关系是地震区划和重大工程场地地震安全性评价的重要内容。在已有的上海及邻近地区地震烈度衰减关系中,统计结果所依据的烈度资料包括历史地震资料,而历史地震资料因震中位置精度不高原则上不宜作为地震烈度衰减关系的统计资料。在借用法工作中,地震动衰减关系所用的距离参数一般采用实际距离,与烈度等震线距离的含义有所不同。基于上述原因,本文仅选用了有近代仪器测定震级的地震,并对等震线的距离参数进行了修正,利用联合衰减统计方法,统计得到上海及邻近地区地震烈度衰减关系。 与以往的类似工作不同之处是:(1)仅选用了有近代仪器测定震级的地震,这样统计结果比较可靠。(2)对距离参数进行了修正,使地震动衰减和烈度衰减关系中的距离参数的定义尽可能保持一致。

A Study of Seismic Intensity Attenuation Law in Vicinity of Shanghai

Shanghai is an international metropolis. The determination of reasonable ascismic standard has a vital significance to a city for earthquake disaster prevention and reduction, economic construction and so cial sustainable development. The seismic ground motion attenuation relationship is an important content in seismic zonation and seismic safety evaluation of engineering sites for key projects.In existing earthquake intensity attenuation relationship in Shanghai and its vicinity, the statistic results based generally on isoseisms which include historical earthquake data. Because the epicenters of his torical earthquake are not precise, in principle, the historical earthquake data are not suitable to seismic intensity attenuation relationship. In borrowing methods, actual distance is used generally as distance pa rameter in seismic ground motion attenuation relationship, which has different meaning from isoseismic distance. Based on above reasons, in this paper, only earthquakes with modern instrument magnitudes are selected, and the distance parameter of isoseisms is revised. The seismic intensity attenuation lawin Shanghai and its vicinity is established by the union attenuation statistical method.Differences between this paper and the former similar work are : (1)Only the earthquakes with modern instrument magnitudes have been selected to make statistic result comparatively reliable; (2)The revised parameter has been adopted so as to maintain definition of distance parameter of seismic ground motion consistent with intensity attenuation relationship as far as possible.