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首先对由深部地震测深剖面观测结果综合归纳出的一个华北地区岩石圈12层三维非均匀实际模型在承受和不承受来自底面的上拱力条件下的应力场进行了数值模拟计算,并根据计算结果对唐山地震孕震条件及长期前兆进行分析研究.其次,再考虑一个唐山及外围地区含有地表及深部断裂的三维不均匀分层岩石圈模型,不对称的加载方式,用长方体形的硬包体、软包体或软—硬包体来模拟唐山大震的孕震区,采用三维有限元法来计算应力场与位移场,并根据计算结果对唐山地震的前兆场时空演化特征及孕震过程进行了分析讨论.所得的初步分析研究结果表明:(1)唐山地震震源位于华北地壳中的一个较坚固的块体之内;(2)地幔上拱力可能在唐山大震孕育中起较大作用;(3)唐山大震的前兆场时空演化特征可用坚固体(硬包体)孕震模式来得到合理的解释.
First of all, the 12-layer lithospheric three-dimensional non-uniform actual model of the lithosphere in North China, which is comprehensively summarized by the deep seismic sounding profile observation results, is numerically simulated with and without under the condition of the upper arch stress from the bottom surface. Based on the results, the seismogenic conditions and long-term precursors of Tangshan earthquake are analyzed.Secondly, a three-dimensional inhomogeneous layered lithosphere model with surface and deep faults in Tangshan and its surrounding areas is also considered. Asymmetric loading method, Inclusions, soft inclusions or soft-hard inclusions are used to simulate the seismogenic zone of Tangshan earthquake. The three-dimensional finite element method is used to calculate the stress field and the displacement field. According to the calculation results, The results of the initial analysis show that: (1) the source of the Tangshan earthquake is located in a relatively strong block in the crust of North China; (2) the upper mantle mantle may be in the middle of the Tangshan earthquake (3) The temporal-spatial evolution characteristics of the precursory field of Tangshan earthquake can be reasonably explained by the seismogenic mode of hard body (hard inclusions).