Dense Global Navigation Satellite System (GNSS) observations enable the development of megathrust interseismic locking models for the southern Kurile subduction zone where many great earthquakes have occurred. Inversion of these data assuming uniform elastic Earth has yielded slip deficit rates that are unreasonably high and/or full locking depth that is unreasonably large. Using the finite element method, here we construct a new Kurile locking model that includes interseismic viscoelastic stress relaxation and non‐uniform compliance of the elastic upper plate. Inverting the same geodetic data using the new subduction zone model alleviates the previously seen unreasonable features in inferred megathrust locking state. In the new model, full locking extends to shallower depths than the downdip limit of some large megathrust earthquakes including the 2003 M_w 8.0 Tokachi‐oki earthquake, supporting the notion of the shrinking of the locked area before the earthquakes and/or propagation of seismic rupture into creeping areas as previously predicted by friction or dynamic rupture models. By modeling the effects of a few recent M 8 earthquakes, we show that postseismic transients of recent earthquakes, although second‐order, should be addressed in deriving megathrust locking models. The locking state near the trench cannot be resolved by the land‐based GNSS data regardless of the improved model rheology and structure, although independent observations, such as slow earthquakes, may be used to speculate on the near‐trench locking state in various part of the margin in the absence of seafloor geodetic observations.

中文翻译：

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南部千岛俯冲带新的超大推力锁定模型结合了粘弹性松弛和上板的非均匀顺应性

密集的全球导航卫星系统（GNSS）的观测值可以为发生许多大地震的南部千岛俯冲带开发巨型推力间震锁定模型。假设均匀的弹性地球，则对这些数据进行反演会产生不合理高的滑脱率和/或不合理大的全锁定深度。在这里，我们使用有限元方法构造了一个新的Kurile锁定模型，该模型包括地震间粘弹性应力松弛和弹性上板的非均匀顺应性。使用新的俯冲带模型反演相同的大地测量数据，可以缓解先前在推论的大推力锁定状态下看到的不合理特征。在新模型中，中号_瓦特8.0十胜OKI地震，支撑锁定区域的地震和/或地震破裂的传播之前收缩的概念到爬行区域如先前通过摩擦或动态破裂模式的预测。通过对最近的几次M 8地震的影响进行建模，我们表明，在推导大推力锁定模型时，尽管是二阶地震，但应解决近期地震的震后瞬变现象。尽管改进了模型的流变学和结构，但无论如何通过陆基GNSS​​数据都无法解决海沟附近的锁定状态，尽管可以使用独立的观测资料（例如慢地震）来推测海峡各部分的近海沟锁定状态。没有海底大地观测的边缘。