Evolution of the oceanic lithosphere inferred from Po/So waves traveling in the Philippine Sea Plate
Evolution of the oceanic lithosphere inferred from Po/So waves traveling in the Philippine Sea Plate
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DOI：
10.1002/2014jb011814
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发表时间：
2015-07
期刊：
影响因子：
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通讯作者：
A. Shito;D. Suetsugu;T. Furumura
中科院分区：
文献类型：
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作者：
A. Shito;D. Suetsugu;T. Furumura
Po/So波的特点是其高频成分和长持续时间在海洋岩石圈中传播的距离很长（可达3000公里）。Po/So波是由小尺度随机不均匀性引起的P波和S波的多次前向散射形成的。为了研究这些不均匀性的性质，Po/So波在菲律宾海板块，其中包括三个地区不同的岩石圈年龄进行了分析。在菲律宾海板块中，Po/So波在最年轻的区域（15 Ma）传播，在较老的区域传播更有效。我们使用二维地震波传播的数值有限差分方法模拟来研究这种传播效率的机制。本研究的结果表明，Po/So波的传播效率的增加取决于海洋岩石圈的年龄，这种关系可以定性地解释为海洋岩石圈的增厚，包括小尺度的非均匀性和内在衰减的减少。这些小尺度的不均匀性可能从大洋岩石圈在扩张脊处形成时起，通过分布在软流圈中的熔体的凝固而在大洋岩石圈中连续形成。
Po/So waves are characterized by their high‐frequency content and long‐duration travel over great distances (up to 3000km) through the oceanic lithosphere. Po/So waves are developed by the multiple forward scattering of P and S waves due to small‐scale stochastic random heterogeneities. To study the nature of these heterogeneities, Po/So waves are analyzed in the Philippine Sea Plate, which consists of three regions with different lithospheric ages. In the Philippine Sea Plate, Po/So waves propagate in the youngest region (15 Ma) and propagate more effectively in older regions. We investigate the mechanism of this propagation efficiency using numerical finite difference method simulations of 2‐D seismic wave propagation. The results of this study demonstrate that the increase in propagation efficiency of Po/So waves depends on the age of the oceanic lithosphere, and this relationship can be qualitatively explained by thickening of the oceanic lithosphere including small‐scale heterogeneities and a reduction in the intrinsic attenuation. These small‐scale heterogeneities may form continuously in oceanic lithosphere from the time of its formation at a spreading ridge, via the solidification of melts distributed in the asthenosphere.