Geodetic Evidence of Time‐Dependent Viscoelastic Interseismic Deformation Driven by Megathrust Locking in the Southwest Japan Subduction Zone
Geodetic Evidence of Time‐Dependent Viscoelastic Interseismic Deformation Driven by Megathrust Locking in the Southwest Japan Subduction Zone
复制标题
日本西南俯冲带巨逆冲锁定驱动的随时间粘弹性震间变形的大地测量证据
DOI：
10.1029/2019gl085551
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发表时间：
2020
影响因子：
5.2
通讯作者：
Oncken Onno
中科院分区：
文献类型：
--
作者：
Li Shaoyang;Fukuda Jun'ichi;Oncken Onno
俯冲带震间形变的时变特征认识不足，通常被忽视。在这里，通过结合世纪之久的水准测量数据和当代全球导航卫星系统（GNSS）速度，我们使用二维粘弹性地震周期模型研究了日本西南部震间形变的时间演化。我们发现，要解释这两个大地测量数据集，需要一个1019Pa·s的稳态大陆地幔粘度。我们的首选模型预测，由于正在进行的巨型逆冲断层锁定驱动的粘性地幔流，在整个地震间期间，表面速度场会发生显着变化，这表明多年GNSS导出的速度场代表了随时间变化的地震间变形的快照。锁固深度和锁固时间对水平和垂直变形模式有重要影响。我们的研究结果突出了震间松弛地幔的重要性，以及在确定南海俯冲带沿着的电流锁定状态时考虑这种效应的必要性。
The time‐variable features of interseismic deformation in subduction zones are poorly understood and commonly ignored. Here, by incorporating century‐long leveling data and contemporary global navigation satellite systems (GNSS) velocities, we investigate the temporal evolution of interseismic deformation in southwest Japan using two‐dimensional viscoelastic earthquake‐cycle models. We find that a steady‐state continental mantle viscosity of 1019Pa·s is required to explain these two geodetic data sets. Our preferred model predicts significant variations in the surface velocity field throughout the entire interseismic period due to viscous mantle flow driven by ongoing megathrust locking, indicating that the multiyear GNSS‐derived velocity field represents a snapshot of time‐varying interseismic deformation. The locking depth and locking time exert significant influences on the horizontal and vertical deformation patterns. Our findings highlight the importance of the interseismically relaxing mantle and the necessity of considering such an effect in determining the current locking state along the Nankai subduction zone.