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本文利用三峡地区近二十余年的地震记录、震源机制、地震宏观等震线、地形变以及地应力测量等资料。作出并讨论了三峡地区的区域b值;研究了该区地晨活动的空间分布特征和地震活动的周期性;作出了北北西向的仙女山断裂带和远安断裂带的平均滑动速率,得到应用历史地震的地震矩求出的平均滑动速率与形变测量所求得的滑动速率基本符合。此外,还讨论了该区中强地震前的地震活动图象,从而得到中强震前小震活动的某些信息。 通过地震活动性与地质构造及区域应力场关系的讨论,认为三峡地区无论是地震活动性,还是区域应力场,均与其相邻地区不同。得出三峡地区地震活动主要受北北西向构造带控制和不具备发生六级以上强震的初步认识。
In this paper, the records of the Three Gorges area for nearly 20 years of seismological records, focal mechanism, seismic macro-isochthonism, topographic changes and in-situ stress measurements and other data. The regional b value of the Three Gorges area was also discussed and discussed. The spatial distribution characteristics of the morning activity and the periodicity of the seismic activity were studied. The average sliding velocities of the Xiannvshan fault zone and the Yuan’an fault zone in the northwest and northwest direction were obtained. The average slip rate obtained from the seismic moment of historical earthquake basically agrees with the slip rate obtained from deformation measurement. In addition, we also discussed the seismic activity images before the moderate-strong earthquakes in the area, so as to obtain some information about the earthquakes before the moderate-moderate earthquakes. Through the discussion of the relationship between seismicity and geological structure and regional stress field, it is considered that the Three Gorges area is different from the adjacent areas in both seismicity and regional stress field. It is concluded that the seismic activity in the Three Gorges area is mainly controlled by the North-West-West structural belt and does not have the strong earthquakes of magnitude 6 or above.