论文部分内容阅读
地壳应力场的研究是地震学中的一个基本课题。本文根据对四个方面资料的分析得到了华北地区(φ30°—41°N,λ105°—124°E)地壳应力场的基本特征。这些资料是:1.地震机制,包括1937年至1979年地震的断层面解和最近十多年中的小地震综合断层面解;2.地震时的地面裂缝;3.公元143年至1976年41次M≥6地震的等震线的长轴方位;4.某些大地震地区的大地测量结果。这是一个一致性相当好的应力场,其最大压应力轴为北东东向,最小压应力轴为北北西向,并且都近于水平向。 从一些大地震的观测事实来看,具有这种一致性应力场的范围要比华北地区大,在远离华北的地方,仍表现出同华北以内相似的地壳应力场。这个事实表明,上述地壳应力场的来源,不限于华北地壳内部,而同更大规模的构造运动有关。欧亚板块、印度洋板块同太平洋板块三者之间的相互作用,以及华北所处远离板块边缘的特殊位置,可能是造成该应力场特征的主要原因。
The crustal stress field research is a basic subject in seismology. In this paper, the basic characteristics of the crustal stress field in North China (φ30 ° -41 ° N, λ105 ° -124 ° E) are obtained based on the analysis of four aspects. These data are: 1. Seismic mechanisms including the fault plane solution of the earthquake from 1937 to 1979 and the complex earthquakes of small earthquakes in the past decade; 2. Ground fissures during earthquakes; 3. AD 143 to 1976 41 long-axis azimuths of isoseismic M≥6 earthquakes; 4. Geodetic results of some large earthquakes. This is a well-consistent stress field with a maximum compressional axis north-east-east and a minimum compressive-stress axis north-north-west, both close to horizontal. From the observation fact of some large earthquakes, the scope of this consistent stress field is larger than that in North China, and the crustal stress field similar to that in North China is still shown far away from North China. This fact shows that the source of the above crustal stress field is not limited to the interior of the crust in North China but is related to the larger tectonic movement. The interaction between the Eurasian plate, the Indian plate and the Pacific plate, and the special position of the North China away from the edge of the plate may be the main reason for the characteristics of the stress field.