Deep structure of the western coast of the Makran subduction zone, SE Iran
Deep structure of the western coast of the Makran subduction zone, SE Iran
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伊朗东南部莫克兰俯冲带西海岸的深层结构
DOI：
10.1016/j.tecto.2019.228314
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发表时间：
2020
期刊：
影响因子：
2.9
通讯作者：
T. Nozad
中科院分区：
文献类型：
--
作者：
K. Motaghi;E. Shabanian;T. Nozad
马克兰俯冲带是世界上记录最少的活动俯冲带之一。本文首次利用远震资料研究了马克兰西部沿海地区地下速度界面的几何形状。这些数据是由两个永久和四个临时地震台站收集的。我们计算P接收函数，并将其与表面波频散数据联合反演，得到二维横波速度模型。利用该模型，我们将接收函数迁移到深度，并在深度9-15 km处显示了两个缓慢向北倾斜的界面，作为吸积楔的底部，27-31 km为莫霍边界。在马克兰海岸线附近2 ~ 9 km的各向异性层上，模拟了0.4 s和1.4 s时Ps脉冲的360度周期振幅变化。我们将这一层解释为马克兰海岸下俯冲带的增生棱镜的标志。一个有趣的观察是，所有的莫霍脉冲倍数都有一个双胞胎。通过接收函数的H-κ叠加，我们发现莫霍边界的双倍可能是位于24.5 ~ 31.5 km深度范围内的薄（~ 4.5 ~ 7 km）高速海洋地壳的标志。我们对西部马克兰的新模型表明，沿海马克兰仍在海洋岩石圈上，填满的海沟位于活跃增生前缘以北约200公里处。这种俯冲的不同几何形状对未来潜在的大型逆冲事件的位置和破裂参数有影响，在Makran西部，这些事件可能对地震危险、海啸传播和俯冲带的热结构建模产生重大影响。
The Makran subduction zone is one of the world's least well documented active subduction zones. We investigate the geometry of subsurface velocity interfaces across the western coastal Makran by means of teleseismic data for the first time. The data were gathered by two permanent and four temporary seismic stations. We calculated P receiver functions and jointly inverted them with surface wave dispersion data to generate a 2-D shear wave velocity model. Employing this model, we migrated receiver functions to depth and show two gently northward dipping interfaces at depths of 9–15 km as the base of the accretionary wedge and 27–31 km as the Moho boundary. 360-degree periodic amplitude variation of the Ps pulse at 0.4 s and 1.4 s are modeled as an anisotropic layer between 2 and 9 km near the Makran shoreline. We interpret this layer as a signature for the accretionary prism of the subduction zone beneath the coastal Makran. One interesting observation is that all multiples of the Moho pulse have a twin. By H-κ stacking of receiver functions, we showed that the twin multiples of the Moho boundary could be a signature of a thin (~ 4.5–7 km) high velocity oceanic crust located at a depth range of 24.5 km to 31.5 km. Our new model for western Makran shows that the coastal Makran is still on the oceanic lithosphere and the filled trench is located almost 200 km north of the active accretion front. This different geometry for the subduction has implications for the location and rupture parameters of future potential megathrust events which, in the western Makran, could have significant influences on seismic hazard, tsunami propagation and thermal structure modeling of the subduction zone.
莫克兰俯冲带的热结构和巨型逆冲孕震潜力
影响因子：
5.2
作者：
Smith G
通讯作者：
Smith G