【摘要】 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。更多还原

【Abstract】 This paper describes the application of the Galerkin finite element method and the treatment of unknown heat flow boundary condition by hybrid method to compute the crustal temperature distribution in North China Bay area. It has been shown that: (1) temperature along the Moho discontinuity is not a constant as generally assumed, but varies from a lower value of about 700℃ at its downwarping portion to a higher value around 810℃ at its upwarping portion; and (2) large shallow earthquakes occurred along a belt of steep thermal gradient just above a low velocity (i. e. low resistivity) zone where the temperature is about 600℃, this may be due to the high temperature below such a zone, weakening the materials of lower crust unable to concentrate stress causing large earthquakes.更多还原