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壳内低速层与大陆多震层有着非常密切的关系。本文用实测人工地震资料,采用更合理的震源深度投影成图方法,将中国西南和西北地区的震源投绘在地壳结构剖面图上,揭示了浅源地震分布与地壳结构构造的某些关系,指出地震多发生在壳内低速层底界面以上,而且集中于低速层顶界面附近。如果深大断裂切穿低速层,则沿着这些断裂的地震活动性明显提高,特别在断裂与低速层的交汇部位,往往是强震易发部位。对引用的文献资料分析后进一步指出,壳内低速层对震源深度的控制作用具有普遍意义,并对这种现象产生的原因作了初步探讨。
The low velocity layer in the crust has a very close relationship with the continental seismicity. In this paper, by using the measured artificial seismic data and using a more reasonable method of source depth projection mapping, the focal sources in the southwestern and northwestern regions of China are plotted on the cross-section of the crust structure, revealing some relations between the shallow seismic distribution and the crustal structure, It is pointed out that the earthquakes mostly occur above the low-velocity bed bottom interface of the shell and are concentrated near the top interface of the low-velocity bed. Seismicity along these faults is significantly enhanced if deep faults cut through the low velocity layer, especially where the fault intersects with the lower velocity layer, and are often prone to strong earthquakes. After analyzing the cited documents and data, it is further pointed out that the control of focal depth by the low velocity layer in the crust is of universal significance. The reasons for this phenomenon are also discussed.