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为了模拟孕育过程,必须先给出孕育过程的特征。本文首先简述了唐山地震的六种主要前兆,在此基础上总结了前兆变化的时间和空间特征。前兆变化在时间上可分为三个阶段:(1)1972年1月—1974年12月,这段时间里发生多种前兆大面积长趋势变化。(2)1975年1月—1976年3月,以唐山为中心100公里范围内出现新的异常,同时外围地区一些测点出现大幅度形变。(3)1976年4月—发震,地形变发生反向或者加速,临震前唐山附近出现地温升高,动物异常集中在唐山周围40公里内。前兆变化的空间特征是,开始在半径200公里范围里出现大面积长趋势异常,后来逐步在半径100公里范围内出现新的异常。根据唐山周围地区的地质构造和上述的前兆时空特征,提出了包含有12条断层和一个硬块体的数学模拟的物理模式,以及进行模拟时的边界条件。
In order to simulate the breeding process, we must first give birth to the characteristics of the process. This paper first briefly describes the six main precursors of the Tangshan earthquake, and summarizes the temporal and spatial characteristics of the precursory changes on this basis. The precursory changes can be divided into three phases in time: (1) January 1972-December 1974, during which time a wide range of precursor large-scale long-term changes have taken place. (2) From January 1975 to March 1976, a new anomaly occurred within a range of 100 kilometers centered on Tangshan. At the same time, some of the measuring points in the peripheral areas changed drastically. (3) In April 1976-onset of the earthquake, the deformation of the terrain reversed or accelerated. Before the earthquake, there was an increase of ground temperature near Tangshan, and the anomaly of animals was concentrated within 40 kilometers around Tangshan. The spatial feature of the precursory change is that large-area long-term anomalies begin to emerge within a radius of 200 km and new anomalies gradually emerge within a radius of 100 km. According to the geological structure of the surrounding area of Tangshan and the above-mentioned precursory space-time features, a physical model of mathematical simulation including 12 faults and a hard block, and the boundary conditions for the simulation are proposed.