Coseismic Deformation From Earthquake Faulting On A Layered Spherical Earth
Coseismic Deformation From Earthquake Faulting On A Layered Spherical Earth
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DOI：
10.1111/j.1365-246x.1996.tb06530.x
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发表时间：
1996-04
影响因子：
2.8
通讯作者：
F. Pollitz
中科院分区：
文献类型：
--
作者：
F. Pollitz
本文提出了一种计算层状球形地球中地震断层作用引起的静态位移场的方法。在浅层，地球分层的特点是在康拉德不连续面和莫霍面的体积和剪切模量急剧跳跃，因此在评估地壳变形时必须考虑。静力平衡方程的解表示为球形和环形分量的叠加，每个分量取决于球谐度和力矩张量。本文将最近应用于层状球形地球上波传播问题的一种方法应用于静态形变场。通过用位移-应力矢量中的不连续性来表示点源，直接导出了特定源几何形状的绿色函数。数值试验验证了该方法的准确性，并说明了球度和分层对计算变形场的影响。在地壳深度，震源100公里范围内，球度的影响一般小于（最大形变的）2%。在球形均匀地球和球形分层地球上计算的变形之间的比较表明，如果忽略地球的分层结构，将引入高达20%的误差。分层的效果是最强的源与一个强大的水平滑动分量。
SUMMARY A method for calculating the static displacement field following earthquake faulting in a layered spherical earth is presented. At shallow levels, the Earth’s layering is characterized by sharp jumps in bulk and shear moduli at the Conrad discontinuity and the Moho and is therefore important to consider when evaluating crustal deformation. The solution to the equations of static equilibrium is represented as a superposition of spheroidal and toroidal components that each depend on spherical harmonic degree and the moment tensor. A method that has recently been applied to the problem of wave propagation on a layered spherical earth is here applied to the static deformation field. By representing the point source in terms of discontinuities in the displacement-stress vector, the Green’s function for a particular source geometry is derived directly. Numerical tests are presented to verify the accuracy of the method and to illustrate the effects of sphericity and layering on the calculated deformation fields. The effect of sphericity is generally less than about 2 per cent (of maximum deformation) within 100 km of an earthquake source at crustal depths. Comparisons between the deformation calculated on a spherical homogeneous earth and spherical layered earth show that up to 20 per cent errors would be introduced if the Earth’s layered structure were ignored. The effect of layering is strongest for sources with a strong horizontal slip component.