Possible evidence for a double crossing phase transition in D" beneath Central America from inversion of seismic waveforms
Possible evidence for a double crossing phase transition in D" beneath Central America from inversion of seismic waveforms
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DOI：
10.1029/2007gl029642
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发表时间：
2007-05-09
影响因子：
5.2
通讯作者：
Fuji, Nobuaki
中科院分区：
文献类型：
--
作者：
Kawai, Kenji;Takeuchi, Nozomu;Fuji, Nobuaki
我们使用相对长周期宽带波形（20 - 200 s）的横向分量作为数据，反演中美洲之下D "层（各向同性）剪切速度的垂直依赖性的地震体波波形数据。我们的模型表明，D“中S速度的增加可能局限于核幔边界以上100 - 200 km的区域，而在核幔边界以上0 - 100 km的区域，S速度与PREM的偏离不明显。这表明在CMB上方100 km的深度处可能存在双交叉（从后钙钛矿回到钙钛矿的逆相变）。分辨率测试表明，我们的方法和资料可以分辨出D“内的垂直速度剖面，尤其是D "的下半部分分辨得更好。
We invert seismic body-wave waveform data for the vertical dependence of ( isotropic) shear-velocity in the D '' layer beneath Central America, using the transverse components of relatively long period broadband waveforms ( 20 - 200 s) as data. Our models suggest that the S-velocity increase in D '' may be localized in the zone from 100 - 200 km above the core-mantle boundary (CMB), while the S-velocity does not significantly deviate from PREM in the zone from 0 - 100 km above the CMB. This suggests the possible existence of a double crossing ( a reverse phase transition from post-perovskite back to perovskite) at a depth of 100 km above the CMB. Resolution tests indicate that our methods and data can resolve the vertical velocity profile within D '', and that the lower half of D '' is especially well resolved.