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溧阳—介休—五原北西向地震条带,是唐山地震后华北地区地震活动最为活跃的地带。通过研究发生在这条带上强震的震源机制,破裂过程,震源参数及迁移特点,发现这条带上的较强地震具有以下特点: 1.M_L≥5.0级地震的破裂面走向均为北西向,与条带的总体走向基本一致。反映这些地震具有沿破裂面方向迁移的特点。 2.强震是从中间向北西及南东两个条带的延伸方向交替扩展迁移的,并且强度有逐个增大的趋势。而1980年3月9日在条带上平遥地区发生M_L=5.7级地震后,再不具备上述迁移,震级增大的特点。 3.截止现在,均以中强震释放能量。其中多数的主压应力P轴与华北地区统一的主压应力方位基本一致,但仍有几个强震与华北地区总体走向明显不同,说明局部条件的影响在这个带上有时可以起主导作用。
The Liyang-Jiexiu-Wulan North-West seismic belt is the most active seismic activity in North China after the Tangshan earthquake. By studying the focal mechanism, rupture process, source parameters and migration characteristics of strong earthquakes in this zone, it is found that the strong earthquakes in this zone have the following characteristics: 1. The rupture planes of M_L≥5.0 earthquakes are both NW To, consistent with the overall trend of the band. It reflects that these earthquakes have the characteristics of migration along the rupture plane. 2. Strong earthquakes are alternately migrated from the middle to the northwest and the two eastward extensional directions of the south and east, and the intensities tend to increase one by one. However, on March 9, 1980, after the M_L = 5.7 earthquake occurred in the Pingyao area on the strip, the above migration did not occur and the magnitude of the earthquake increased. 3. As of now, all the strong earthquakes release energy. Most of the P-axis of principal compressive stress is basically the same as the unified principal compressive stress of North China, but there are still several strong earthquakes and North China. The overall trend is obviously different from that of North China, indicating that the influence of local conditions can sometimes play a leading role in this zone.