Anatomy of large earthquakes in North China
Anatomy of large earthquakes in North China
复制标题
华北地区大地震解剖
DOI：
10.1016/j.jseaes.2022.105342
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发表时间：
2022-07
期刊：
影响因子：
--
通讯作者：
Dong Yan
中科院分区：
文献类型：
--
作者：
Hongli Li;You Tian;Dapeng Zhao;Dong Yan
·大多数大型事件发生在高V区或靠近低V区和高V区之间的边界。·中下地壳显著的低V和高σ异常反映了地壳流体。·地壳流体可能起源于大地幔楔中的热湿上涌流。·地壳流体影响了陆内大地震的成核和发生。我们提供了1966年至2021年间发生在华北地区的26次地壳大地震（M5.6-7.8）的震源区详细的三维各向同性P波和S波速度（Vp、Vs）图像和Vp方位各向异性。大部分大地震位于高速（高V）带或靠近低速（低V）和高V异常之间的边界。在几乎所有源区的中下地壳都显示出明显的低V和高泊松比（高σ）异常，可能反映了地壳流体。低V、高σ异常可使其上的脆性孕震层局部减薄、弱化。地壳流体可能来源于东亚大地幔楔（BMW）中的热湿上涌流，这是由于BMW中的角流和地幔过渡带中停滞的太平洋板片的深度脱水反应造成的。
• Most of the large events occurred in high-V or close to the boundary between low-V and high-V zones. • Prominent low-V and high-σ anomalies in the middle and lower crust reflect crustal fluids. • Crustal fluids may originate from hot and wet upwelling flows in the big mantle wedge. • Crustal fluids affected the nucleation and generation of intracontinental large earthquakes. We present detailed 3-D isotropic P and S wave velocity (Vp, Vs) images and Vp azimuthal anisotropy in source areas of 26 large crustal earthquakes (M5.6–7.8) that occurred in North China during 1966 to 2021. Most of the large earthquakes are located in high-velocity (high-V) zones or close to the boundary between low-velocity (low-V) and high-V anomalies. Prominent low-V and high Poisson’s ratio (high-σ) anomalies are revealed in the middle and lower crust under almost all the source areas, which may reflect crustal fluids. The low-V and high-σ anomalies may cause local thinning and weakening of the brittle seismogenic layer above them. The crustal fluids may originate from hot and wet upwelling flows in the big mantle wedge (BMW) beneath East Asia due to corner flows in the BMW and deep dehydration reactions of the stagnant Pacific slab in the mantle transition zone.
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DOI：
10.1029/2019jb018600
发表时间：
2020
期刊：
Journal of Geophysical Research: Solid Earth
影响因子：
--
作者：
Zhiteng Yu;Dapeng Zhao
通讯作者：
Dapeng Zhao