Recent megathrust events in Tohoku (Japan), Maule (Chile), and Sumatra (Indonesia) were well recorded. Much has been learned about the dominant physical processes in megathrust zones: (partial) locking of the plate interface, detailed coseismic slip, relocking, afterslip, viscoelastic mantle relaxation, and interseismic loading. These and older observations show complex spatial and temporal patterns in crustal deformation and displacement, and significant differences among different margins. A key question is whether these differences reflect variations in the underlying processes, like differences in locking, or the margin geometry, or whether they are a consequence of the stage in the earthquake cycle of the margin. Quantitative models can connect these plate boundary processes to surficial and far-field observations. We use relatively simple, cyclic geodynamic models to isolate the first-order geodetic signature of the megathrust cycle. Coseismic and subsequent slip on the subduction interface is dynamically (and consistently) driven. A review of global preseismic, coseismic, and postseismic geodetic observations, and of their fit to the model predictions, indicates that similar physical processes are active at different margins. Most of the observed variability between the individual margins appears to be controlled by their different stages in the earthquake cycle. The modeling results also provide a possible explanation for observations of tensile faulting aftershocks and tensile cracking of the overriding plate, which are puzzling in the context of convergence/compression. From the inversion of our synthetic GNSS velocities we find that geodetic observations may incorrectly suggest weak locking of some margins, for example, the west Aleutian margin.

中文翻译：

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俯冲带地震循环的大地测量特征：对深部过程的模型约束

最近在东北（日本）、莫莱（智利）和苏门答腊（印度尼西亚）发生的特大逆流事件得到了很好的记录。关于超逆冲带的主要物理过程已经了解了很多：板块界面的（部分）锁定、详细的同震滑动、重新锁定、后滑、粘弹性地幔松弛和地震间加载。这些和较早的观测表明地壳变形和位移的时空模式复杂，不同边缘之间存在显着差异。一个关键问题是这些差异是否反映了潜在过程的变化，如锁定或边缘几何形状的差异，或者它们是否是边缘地震周期阶段的结果。定量模型可以将这些板块边界过程与地表和远场观测联系起来。我们使用比较简单，循环地球动力学模型，以隔离巨型逆冲循环的一阶大地测量特征。俯冲界面上的同震和随后的滑动是动态（和一致）驱动的。对全球震前、同震和震后大地测量观测及其对模型预测的拟合的回顾表明，类似的物理过程在不同的边缘活跃。大多数观察到的单个边缘之间的变化似乎是由它们在地震周期中的不同阶段控制的。建模结果还为观察到的拉伸断层余震和覆盖板块的拉伸开裂提供了可能的解释，这在收敛/压缩的背景下令人费解。