An elastic plate model for interseismic deformation in subduction zones
An elastic plate model for interseismic deformation in subduction zones
复制标题
俯冲带震间变形的弹性板块模型
DOI：
10.1029/2009jb006611
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发表时间：
2010
影响因子：
--
通讯作者：
M. Simons
中科院分区：
文献类型：
--
作者：
R. Kanda;M. Simons
在俯冲带附近的地震间地表形变的大地测量观测经常使用简单的运动学弹性位错模型（EDM）解释。在这项理论研究中，我们开发了一个动态EDM，模拟板块俯冲在地震间隔期间（弹性俯冲板块模型（ESPM））只有2个自由度比成熟的背滑模型（BSM）：弹性板厚度和弯曲应力的分数，由于弯曲在沟槽中不断释放。与假定两个板块的稳态变形可以忽略不计的BSM不同，ESPM包括俯冲和覆盖板块的变形（由于板块厚度），同时仍然保持俯冲和覆盖板块之间的收敛速度的正确意义，以及当在许多地震周期上积分时，两个板块之间的净稳态垂直偏移为零。ESPM链接弹性板块挠曲过程的震间变形，并有助于澄清在什么条件下的BSM是适合于拟合地震间的大地测量数据在收敛的利润。我们表明，ESPM是相同的BSM在零板厚的极限情况下，从而提供了一个替代的动机BSM。ESPM还为将BSM应用于任何巨型推力界面几何形状提供了一致的约定。即使在不可忽略的板块厚度的情况下，由ESPM预测的变形场减少到的BSM，如果应力相关的板块弯曲在沟槽中被释放，无论是连续和完全在浅的深度在地震间隔期间或深的俯冲带（低于100公里）。然而，如果这些应力中的至少一部分没有在俯冲带的浅部连续释放（通过地震或地震事件），则这两个模型的预测表面速度在与沟槽的水平距离处可能会有显著差异，相当于有效震间锁定深度的几倍。
Geodetic observations of interseismic surface deformation in the vicinity of subduction zones are frequently interpreted using simple kinematic elastic dislocation models (EDM). In this theoretical study, we develop a kinematic EDM that simulates plate subduction over the interseismic period (the elastic subducting plate model (ESPM)) having only 2 more degrees of freedom than the well-established back slip model (BSM): an elastic plate thickness and the fraction of flexural stresses due to bending at the trench that are released continuously. Unlike the BSM, in which steady state deformation in both plates is assumed to be negligible, the ESPM includes deformation in the subducting and overriding plates (owing to plate thickness), while still preserving the correct sense of convergence velocity between the subducting and overriding plates, as well as zero net steady state vertical offset between the two plates when integrated over many seismic cycles. The ESPM links elastic plate flexure processes to interseismic deformation and helps clarify under what conditions the BSM is appropriate for fitting interseismic geodetic data at convergent margins. We show that the ESPM is identical to the BSM in the limiting case of zero plate thickness, thereby providing an alternative motivation for the BSM. The ESPM also provides a consistent convention for applying the BSM to any megathrust interface geometry. Even in the case of nonnegligible plate thickness, the deformation field predicted by the ESPM reduces to that of the BSM if stresses related to plate flexure at the trench are released either continuously and completely at shallow depths during the interseismic period or deep in the subduction zone (below ∼100 km). However, if at least a portion of these stresses are not continuously released in the shallow portion of the subduction zone (via seismic or aseismic events), then the predicted surface velocities of these two models can differ significantly at horizontal distances from the trench equivalent to a few times the effective interseismic locking depth.