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中国东北地区有一条震源深度达600公里的深震带,从震源剖面投影可以明显地看出,它是西太平洋板块俯冲的结果,俯冲的角度约为26°。 根据板块学说,建立了一个板块俯冲模型,主要考虑地幔物质和岩石层板块的热传导,计算了板块俯冲到一定深度时的温度分布。结果表明,西太平洋板块俯冲到中国东北地区深度达600公里时,其中心温度约为1200℃,仍比周围地幔物质的温度低得多,因而能产生弹性断裂,发生地震。 震源机制的结果表明,中国东北地区深震的主压应力轴方位为93°—113°,正好迎着板块俯冲的方向,仰角为27°—28°,与板块俯冲的角度大体一致。以上结果说明中国东北深震是西太平洋板块俯冲到中国东北大陆之下造成的。
In the northeastern region of China, there is a deep seismic zone with a focal depth of 600 km. As can be clearly seen from the projection of the source profile, it is the result of subduction of the western Pacific plate, with a subduction angle of about 26 °. According to the theory of plate, a plate subduction model is established, which mainly considers the heat conduction of the mantle material and lithosphere, and calculates the temperature distribution when the plate subducts to a certain depth. The results show that when the western Pacific plate subducted to a depth of 600 km in the northeast of China, the central temperature was about 1200 ° C, which was still much lower than the temperature of the surrounding mantle material, resulting in elastic faults and earthquakes. The results of focal mechanisms show that the principal compressive stress axis of deep earthquakes in northeastern China is located at 93 ° -113 °, which corresponds to the direction of plate subduction with an elevation angle of 27 ° -28 °, which is generally consistent with the plate subduction angle. The above results show that the deep earthquakes in northeast China are caused by the subduction of the western Pacific plate beneath the northeast continent of China.