D″ anisotropy beneath Southeast Asia
D″ anisotropy beneath Southeast Asia
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D″ 东南亚地下的各向异性
DOI：
10.1029/2006gl028965
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发表时间：
2007
影响因子：
5.2
通讯作者：
M. Simpson
中科院分区：
文献类型：
--
作者：
C. Thomas;J. Wookey;M. Simpson
天山地区吉尔吉斯地震台网记录的班达海和弗洛雷斯海地区的地震显示了东南亚最低地幔各向异性的证据。在应用接收器侧校正之后，针对ScS相位测量剪切波分裂。单个结果显示在测量的时间滞后和快速方向上的分散，但是叠加这些结果给出了0.8 ± 0.04 s和43 ± 4度的稳定估计值。这相当于一个快剪切波，其偏振偏离水平（在反弹点）约9度。最简单的解释模型是横向各向同性介质，稍微向东倾斜，推断各向异性为0.25%。这与该区域VSH > VSV的先前观测结果一致。可能解释观察到的各向异性的情景包括剪切熔体口袋或与太平洋板块和印度板块的古俯冲相关的对齐后钙钛矿晶体。
Earthquakes from the Banda Sea and Flores Sea region recorded at the Kyrgyz Network in the Tien Shan region show evidence for anisotropy in the lowermost mantle beneath South East Asia. Shear‐wave splitting is measured for the ScS phase after a receiver‐side correction is applied. Individual results show scatter in measured time lag and fast direction, but stacking these gives a stable estimate of 0.8 ± 0.04 s and 43 ± 4 degrees. This equates to a fast‐shear wave with a polarisation deviation from horizontal (at the bounce point) of around 9 degrees. The simplest model to explain is a transversely isotropic medium with a slight dip to the east, and an inferred anisotropy of ∼0.25%. This is compatible with previous observations of VSH > VSV for this region. Scenarios which might explain the observed anisotropy include sheared melt pockets or aligned post‐perovskite crystals associated with palaeosubduction of the Pacific plate and Indian plate.