HORIZONTAL LAYERED STRUCTURE WITH HETEROGENEITY BENEATH CONTINENTS AND ISLAND ARCS FROM PARTICLE ORBITS OF LONG-PERIOD P WAVES
HORIZONTAL LAYERED STRUCTURE WITH HETEROGENEITY BENEATH CONTINENTS AND ISLAND ARCS FROM PARTICLE ORBITS OF LONG-PERIOD P WAVES
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长周期P波粒子轨道的大陆和岛弧下非均质水平层状结构
DOI：
10.1111/j.1365-246x.1996.tb04056.x
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发表时间：
1996
影响因子：
2.8
通讯作者：
T. Nishimura
中科院分区：
文献类型：
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作者：
T. Nishimura
我们研究了用全球地震台网观测的长周期(约20 S)P波的粒子轨道。通过对发生在300公里以下的60次地震的25个台站记录的84幅三分量地震记录的分析，利用协方差矩阵法，用三组特征值和特征向量对轨道进行了定量估计。用标准水平层状结构模型(Iasp91)解释了大陆上各台站记录的P波特征值。另一方面，在靠近岛弧的台站观测到的轨道不仅受水平层状结构的影响，而且还受俯冲板块、地幔底辟等非均质性的影响。在平面P波单次散射模型的基础上，我们用各向同性散射系数G0来量化非均质性。将理论本征值与观测值进行拟合，我们估计大陆以下地壳和上地幔的G0小于0.0005公里-1，岛弧下结构的平均G0约为0.0015-0.003公里-1。
We investigate the particle orbits of long-period (about 20 s) P waves observed with the global seismic network. By analysing 84 three-component seismograms recorded at 25 stations from 60 earthquakes occurring beneath 300 km, we quantitatively evaluate the orbits by three sets of eigenvalues and eigenvectors, using a covariance matrix method. The eigenvalues for P waves recorded at stations located on continents are explained by the standard horizontal layered structure model (iasp91). On the other hand, the orbits observed at stations close to island arcs are affected not only by the horizontal layered structure but also by heterogeneity due to subducting plates, mantle diapirs and so on. On the basis of a single-scattering model for a plane P wave, we quantify the heterogeneities by an isotropic scattering coefficient g0. Fitting the theoretical eigenvalues to the observed ones, we estimate g0 for the crust and upper mantle beneath continents to be less than 0.0005 km-1, and the mean g0 for the structure beneath island arcs to be about 0.0015 to 0.003 km-1.