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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Dynamics of the India-Eurasia collision zone
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Dynamics of the India-Eurasia collision zone

机译：印度-欧亚碰撞带的动力学

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We present simple new dynamic calculations of a vertically averaged deviatoric stress field (over a depth average of 100 km) for Asia from geodetic, geologic, topographic, and seismic data. A first estimate of the minimum absolute magnitudes and directions of vertically averaged deviatoric stress is obtained by solving force balance equations for deviatoric stresses associated with gravitational potential energy differences within the lithosphere plus a first-order contribution of deviatoric stresses associated with stress boundary conditions. This initial estimate of the vertically averaged deviatoric stress field is obtained independent of assumptions about the rheology of the lithosphere. Absolute magnitudes of vertically averaged deviatoric stresses vary between 5 and 40 MPa. Assuming bulk viscous behavior for the lithosphere, the magnitudes of deviatoric stresses, together with the magnitudes of strain rates inferred from Quaternary fault slip rate and GPS data, yield vertically averaged effective viscosities for Tibet of 0.5-5 x 10(22) Pa s, compared with 1-2.5 x 10(23) Pa s in more rigid areas elsewhere in the region. A forward modeling method that solves force balance equations using velocity boundary conditions allows us to refine our estimates of the vertically averaged effective viscosity distribution and deviatoric stress field. The total vertically averaged deviatoric stress and effective viscosity field are consistent with a weak lower crust in Tibet; they are consistent with some eastward motion of Tibet and south China lithosphere relative to Eurasia; and they confirm that gravitational potential energy differences have a profound effect on the spatially varying style and magnitude of strain rate around the Tibetan Plateau. Our results for the vertically averaged deviatoric stress argue for a large portion of the strength of the lithosphere to reside within the seismogenic upper crust to get deviatoric stress magnitudes there to be as high as 100-300 MPa (in accord with laboratory and theoretical friction experiments indicating that stress drops in earthquakes are small fractions of the total deviatoric stress). [References: 80]
机译：我们提供了根据大地，地质，地形和地震数据对亚洲垂直平均应力场（平均深度超过100 km）进行简单的新动态计算。通过求解与岩石圈内与重力势能差相关的偏应力的力平衡方程以及与应力边界条件相关的偏应力的一阶贡献，可以获得垂直平均偏应力的最小绝对值和方向的第一估计。垂直平均偏斜应力场的初始估计是独立于岩石圈流变性的假设而获得的。垂直平均偏差应力的绝对大小在5到40 MPa之间变化。假设岩石圈的整体粘性行为，偏应力的大小，以及根据第四纪断层滑动率和GPS数据推断出的应变率的大小，对西藏产生的垂直平均有效粘度为0.5-5 x 10（22）Pa s，在该区域其他地方较刚性的区域则为1-2.5 x 10（23）Pa s。一种使用速度边界条件求解力平衡方程的正向建模方法，使我们可以改进垂直平均有效粘度分布和偏应力场的估计。垂直平均总偏斜应力和有效黏度场与西藏下地壳弱相一致。它们与西藏和华南岩石圈相对于欧亚大陆的一些东移一致。他们证实，重力势能差对青藏高原周围的空间变化样式和应变率大小有深远的影响。我们的垂直平均偏向应力结果表明，岩石圈的大部分强度都位于发震的上地壳内，从而使偏向应力幅值高达100-300 MPa（与实验室和理论摩擦实验一致）表明地震中的应力下降仅占总偏应力的一小部分）。 [参考：80]

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