Constraints from GPS measurements on the dynamics of deformation in Anatolia and the Aegean
Constraints from GPS measurements on the dynamics of deformation in Anatolia and the Aegean
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DOI：
10.1002/2016jb013382
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发表时间：
2016-12-01
影响因子：
3.9
通讯作者：
Nocquet, Jean-Mathieu
中科院分区：
文献类型：
--
作者：
England, Philip;Houseman, Gregory;Nocquet, Jean-Mathieu
我们估计在安纳托利亚和爱琴海的岩石圈的强度，和边界力作用于它，使用一个动力学模型，将岩石圈作为一个薄的流体片变形响应重力势能的变化。该模型有一个自由的材料参数，幂律指数，n，垂直平均岩石圈的流变学，和两个参数，指定每单位长度的力施加到其边缘。最适合346个可靠的GPS站点的速度的这个模型的解决方案需要在每年10到100纳应变的应变率下10（22）到10（21）Pa·s的岩石圈有效粘度。在阿拉伯-安纳托利亚边界的最佳拟合力是一致的，由于那里的高地形的岩石静压力，和在努比亚-爱琴海边界的力是一致的，在岩石静压力的对比跨越该边界。没有额外的力量，从“板卷回滚”或由于地幔对流的基底牵引，是需要解释的意见。这些结果得到了近似解析解的标度关系的支持。岩石圈的粘度和偏应力之间的反比关系产生强烈的缓慢变形区在爱琴海南部和安纳托利亚中部的运动类似于那些微板块。大地应变率在该地区的分布，正常和走滑断层之间的分区，解释边界条件，重力势能的内部变化之间的相互作用，和幂律流变的岩石圈。
We estimate the strength of the lithosphere in Anatolia and the Aegean, and the boundary forces acting upon it, using a dynamical model that treats the lithosphere as a thin fluid sheet deforming in response to variations in gravitational potential energy. This model has one free material parameter, the power law exponent, n, of the vertically averaged rheology of the lithosphere, and two parameters that specify the forces per unit length applied to its edges. Solutions to this model that best fit the velocities of 346 reliable GPS sites require an effective viscosity of the lithosphere of 10(22) to 10(21) Pa s at strain rates of 10 to 100 nanostrain per year. The best-fitting force at the Arabia-Anatolia boundary is consistent with the lithostatic pressure due to the high topography there, and the force at the Nubia-Aegean boundary is consistent with the contrast in lithostatic pressure across that boundary. No additional force, from "slab rollback" or basal tractions due to convection in the mantle, is required to explain the observations. These results are supported by scaling relations derived from approximate analytical solutions. The inverse relationship between the viscosity of the lithosphere and deviatoric stress produces strong slowly deforming regions in the Southern Aegean and Central Anatolia whose motions resemble those of microplates. The distribution of geodetic strain rates within the region, and the partitioning between normal and strike-slip faulting, are explained by the interplay between boundary conditions, internal variations in gravitational potential energy, and the power law rheology of the lithosphere.