The three-dimensional shear wave structure in the mantle by overtone waveform inversion - I. Radial seismogram inversion
The three-dimensional shear wave structure in the mantle by overtone waveform inversion - I. Radial seismogram inversion
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泛音波形反演地幔三维剪切波结构——一、径向地震图反演
DOI：
10.1111/j.1365-246x.1987.tb05189.x
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发表时间：
1987
影响因子：
2.8
通讯作者：
T. Tanimoto
中科院分区：
文献类型：
--
作者：
T. Tanimoto
摘要通过对径向分量地震记录波形的反演，得到了深达900 km的地幔三维剪切波结构。径向分量地震图包含以波包形式环绕地球的大振幅泛音信号，有时称为X1，X2，X3，.我们使用包含R1，X1和X2并在2和10 mHz之间滤波的数据。它表明，除非每个地震图加权，所有的地震图不是一致的。只有大地震的数据进行了拟合，最终的速度异常是由少量的大地震数据的偏见。分辨率在浅层较好，在约400至500公里的中间深度范围变差，然后在更大的深度范围（600至900公里）变得更好。即使我们只使用球体模式数据，浅层结构中的速度异常也显示出与地球表面岩石年龄的良好相关性。在600 ~ 900 km的较深区域，南美洲显示出快速的速度异常，这可能表明那里的板片穿透超过700 km。另一个显示出快速速度异常的区域是马里亚纳海沟，但其他俯冲区域没有显示出这种特征。
Summary. The three-dimensional (3-D) shear wave structure of the mantle, down to the depth of about 900 km, is obtained by inverting waveforms of radial component seismograms. Radial component seismograms contain large amplitude overtone signals which circle the Earth as wave packets and are sometimes called X1, X2, X3, … We use data which contain R1, X1 and X2 and filtered between 2 and 10mHz. It is shown that, unless each seismogram is weighted, all seismograms are not fitted uniformly. Only data from large earthquakes are fitted and the final velocity anomalies are biased by the small number of large earthquake data. Resolution is good at shallow depths, becomes worse in the intermediate depth range between about 400 and 500 km and then becomes better at greater depth ranges (600–900km). Even though we use only spheroidal mode data, velocity anomalies in the shallow structure show excellent correlation with the age of the surface rocks of the Earth. In the deeper regions, between about 600 and 900km, South America shows a fast velocity anomaly which may indicate the slab penetration beyond 700 km there. Another region which shows a fast velocity anomaly is the Mariana trench, but other subduction regions do not show such features.