The Method of Spatially Smoothed Seismicity Parameters in Consideration of Seismotectonic Background and Its Application to Seismic Hazard Estimation

In this study, the North China seismic region was selected as the study area, and evaluation of seismic hazard using the spatial smoothing seismicity model was performed. Firstly, the study area is divided into grids, and some parameters （e. g. b-value, Mo, Me, azimuth and M-L relationship ） for each seismotectonic model were assigned. Secondly, using elliptical smoothing based on a seismotectonic background model, the statistical earthquake incidence rate in each grid is successively calculated. Lastly, the relevant ground motion attenuation relationship is chosen to assess seismic hazard of general sites. The maps for the distribution of horizontal peak ground acceleration with 10% probability of exceedance in 50 years were obtained by using the seismic hazard analysis method based on grid source. This seismicity model simplifies the methodology of probabilistic seismic hazard analysis, especially appropriate for those places where seismic tectonics is not yet clearly known. This method can provide valuable references for seismic zonation and seismic safety assessment for significant engineering projects.

依据啮齿目动物生物鉴定资料炭黑不应划为对人致癌物

为数众多的流行病学研究都未能证明职业性接触炭黑是否会增加人们罹患肺癌的危险。炭黑对于小鼠（吞食、皮肤接触或吸入）、仓鼠（吸入）、兔子（皮肤接触或吸入）、灵长类动物（皮肤接触或吸入）和大鼠（吞食）来说都不是致癌物。只有大鼠进行的从气管内配给或吸入的实验才证明，称为良性囊状角化扁平细胞（KSC）肿瘤的良性及恶性肺肿瘤和损害会明显增加。炭黑诱发的肺肿瘤（包括KSC损害）仅在大鼠身上发生。一个专家小组在评审大鼠身上用钛白粉（二氧化钛）或对．芳族聚酰胺（一种小纤维）引发的损害后，得出结论说，在人类身上是见不到KSC损害的。人类的肺肿瘤主要位于支气管气道中，而在大鼠身上，肺肿瘤则生长在主质中，并且最初是发生在肺泡内。大鼠对炭黑的这一物种特有反应（肿瘤生长和KSC损害）在任何其它实验物种身上均未曾见到，也未见报告说在人类身上有这一物种特有反应。这一物种特有反应有力地证明，在评估炭黑对人类的危害性时，大鼠吸入炭黑的生物鉴定结果不得视为与其有直接的关系。因此，依据啮齿目动物的生物鉴定资料，对于人类而言，炭黑不应划为致癌物。