A waveform migration for the investigation of P wave structure at the top of D″ beneath northern Siberia
A waveform migration for the investigation of P wave structure at the top of D″ beneath northern Siberia
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DOI：
10.1029/2000jb900388
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发表时间：
2001-03
影响因子：
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通讯作者：
M. Freybourger;S. Chevrot;F. Krüger;U. Achauer
中科院分区：
文献类型：
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作者：
M. Freybourger;S. Chevrot;F. Krüger;U. Achauer
我们介绍了第一次下地幔的波形偏移，重点是西伯利亚北部最低400公里的地幔。我们迁移了西欧记录的千岛群岛地区地震的垂直分量P波地震记录。重点研究了在核幔边界反射的直接P波和PCP波之间的时间窗，并研究了PCP前兆的起源。这些数据因其良好的信噪比而被选中，由P波束确定的震源时间函数进行去卷积。我们观察到了一个有限大小的散射体的特征，该散射体位于75°N，85°E附近，相对于∼模型，视深度为IASP2650公里。它的标尺长度可能在100公里左右。该天体以各向异性散射图为特征，可能与核-地幔边界附近存在一个古老的俯冲板块有关。
We present the first waveform migration for the lower mantle, focusing on the lowermost 400 km of the mantle beneath northern Siberia. We migrate vertical component P wave seismograms recorded in western Europe for earthquakes located in the Kuril Islands region. We focus on the time window between the direct P wave and the PcP wave, reflected at the core-mantle boundary, and we investigate the origin of PcP precursors. The data, selected for their good signal-to-noise ratio, are deconvolved by the source time function determined by the beam of the P wave. We observe the signature of a finite size scattering object located around 75°N, 85°E, at an apparent depth of ∼2650 km with respect to the IASP91 model. Its scale length is probably of the order of 100 km. This object is characterized by an anisotropic scattering diagram and may be related to the presence of an ancient subducted plate near the core-mantle boundary.