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根据地下三百米深处的温度与居里面深度分布的资料,利用伽勒金有限元法配合未知边界流量的杂交法,计算了渤海湾邻近的地壳剖面的温度分布。结果表明:(1)莫氏面上的温度不是常数,最高处可达810℃;(2)大地震往往发生在温度与重力梯度带附近而温度较低密度较小的一侧;(3)本区地壳低速层的温度约为600℃,在该层以下,随着温度的增高,介质的弹性模量或粘滞系数显著减少,而泊松比反而增大,故地壳深部的剪应力减小,这说明大陆内部地震大多发生在低速层以上的原因。
According to the temperature and depth distribution in the depth of 300 meters underground, the temperature distribution in the crustal section adjacent to Bohai Bay was calculated by using the Gallen ’s finite element method combined with the unknown boundary flow. The results show that: (1) the temperature on the Mohs surface is not constant, and the maximum is up to 810 ° C; (2) the large earthquakes often occur near the temperature and gravity gradient zones with the lower temperature; (3) The temperature of crustal low-velocity zone in this area is about 600 ℃. Below this level, with the increase of temperature, the elastic modulus or viscosity coefficient of the medium decreases significantly, but the Poisson’s ratio increases. Therefore, the shear stress in deep crust This shows that most of the earthquakes in mainland China occur at low velocity.