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本文采用地震学P波初动资料求解小地震综合断层面解方法,使用115个地震台的4000余个小地震初动资料,测定了华北地区近年小震应力场。提出在同一地震构造带上,小震断层面解的主压应力方向具有一致性。大地震前、后区域应力场可能发生变化。分析了1981年菏泽5.9级地震前小震应力场的动态变化特征等。指出随着大地震的发生,区域应力场发生变化是形成复杂的多层次的地震活动性的基础。最后,对华北地区应力场特征及高应力背景区等做了讨论。
In this paper, we use the seismic P-wave initial data to solve the complex earthquakes of small earthquakes. Using the initial data of more than 4,000 small earthquakes in 115 seismostats, the small-field stress fields in North China were measured. It is proposed that the direction of the principal compressive stress of the fault plane solutions of small earthquakes is consistent on the same seismic zone. The regional stress field may change before and after the earthquake. The dynamic characteristics of the small earthquake stress field before the MS 5.9 Heze earthquake are analyzed. It is pointed out that with the occurrence of a large earthquake, the change of regional stress field is the basis for the formation of complex and multi-level seismicity. Finally, the stress field characteristics and high stress background area in North China are discussed.