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运用格点尝试法推断了沂沭断裂带现代构造应力场的分段受力环境,初步分析了沂沭断裂带及其两侧块体在中强地震前后构造应力环境的变化特点。其变化特点为:震前3 个区主应力方位值有一个明显的增大趋势;3 个区的增大变化为不同步;沂沭带主应力方位值增大出现时间较晚,增幅较大,为阶跃性增大;山东东部的主张应力方位值幅度增大,持续达4 年以上。震后3 个区主应力方位值出现明显的同步性回落,沂沭带的主应力降幅巨大。
The gridded stress environment of the Yishu fault zone is deduced by using the lattice point method. The changes of the tectonic stress environment of the Yishu fault zone and its two lateral blocks before and after the moderate-strong earthquakes are analyzed preliminarily. The characteristics of the changes are as follows: the principal stress in the three areas before the earthquake has a significant increase in the azimuth; the increase in the three areas does not change synchronously; the increase of the azimuth of the main stress in the Yishu Zone appears later and increases greatly , A step-by-step increase; the magnitude of the claimed stress in eastern Shandong increased for more than four years. After the earthquake, the main stress of the three districts showed a significant synchronicity, and the main stress of Yishu belt dropped greatly.