Variations of Velocity and Attenuation Anisotropy Structures in the Uppermost Inner Core Beneath the Central Pacific Region
Variations of Velocity and Attenuation Anisotropy Structures in the Uppermost Inner Core Beneath the Central Pacific Region
复制标题
中太平洋地区最上层内核速度和衰减各向异性结构的变化
DOI：
10.1029/2019gl084258
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发表时间：
2019
影响因子：
5.2
通讯作者：
A. Fan
中科院分区：
文献类型：
--
作者：
Jialing Qin;Xinlei Sun;A. Fan
利用 PKIKP 和 PKIKP 走时和振幅比，我们研究了太平洋中部地区下方内核最上面 100 公里的速度和衰减各向异性结构。我们的结果表明，经度从大约 180°E 到 190°E 有明显变化。西太平洋以下，速度各向异性较弱，衰减较大（Qp~200），而东太平洋以下，速度各向异性较强（3.3%），衰减较小（Qp范围为400~150）。此外，速度各向异性和衰减各向异性彼此相关。我们的结果表明，内核的生长可能与核地幔边界的热不均匀性有关。这些不均匀性可能会影响最上面内核的定向热流或变形过程，导致不同的铁晶体排列，并导致各向异性结构的横向变化。
Using PKIKP and PKiKP travel times and amplitude ratios, we examine the velocity and attenuation anisotropy structures in the uppermost 100 km of the inner core beneath the central Pacific region. Our results indicate a clear change from approximately 180°E to 190°E longitude. Below the western Pacific, velocity anisotropy is weak and attenuation is high (Qp ~200), whereas below the eastern Pacific, velocity anisotropy is strong (3.3%) and attenuation is low (Qp ranges from 400 to 150). Furthermore, the velocity and attenuation anisotropies are correlated with each other. Our results indicate that the growth of the inner core may be coupled with core mantle boundary thermal heterogeneities. The heterogeneities may affect directional heat flow or deformational processes in the uppermost inner core, cause different iron crystal alignments, and result in lateral variations in anisotropy structures.