Autoregressive estimation of the splitting matrix of free-oscillation multiplets
Autoregressive estimation of the splitting matrix of free-oscillation multiplets
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DOI：
10.1046/j.1365-246x.2000.00058.x
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发表时间：
2000-04
影响因子：
2.8
通讯作者：
G. Masters;G. Laske;F. Gilbert
中科院分区：
文献类型：
--
作者：
G. Masters;G. Laske;F. Gilbert
摘要最近，由迅速增长的全球地震台网记录的大地震产生了大量高质量的数据。这些新数据使我们能够开发新的技术来确定多重态的耦合和分裂特性，从而确定地球的三维结构。目前的技术往往是计算密集和非线性的，需要详细的震源模型(这可能无法用于自由振荡研究中使用的大型且往往复杂的事件)。在这里，我们介绍了一种新的技术，它允许我们在不知道震源的情况下，用几个步骤来求解分裂矩阵的最一般形式。该方法利用了单次地震记录的某些线性组合具有自回归特性，其传播算子矩阵与指数分裂矩阵有关.为了求取传播算子矩阵，只需使用参考地球模型的位移标量和仪器标定来执行两步线性反演.可以(并且通常必须)使用多个事件来允许检索传播者矩阵。从传播矩阵恢复分裂矩阵是很简单的，正是分裂矩阵的元素对地球的三维结构提供了线性约束。我们使用来自10个大地震的近900个垂直分量记录来说明该技术，以恢复各种不同倍增的分裂矩阵。结果以分裂函数的形式给出，其中包括待确定的第一类稳健滞弹性分裂函数。
SUMMARY Recent, large earthquakes, recorded by the rapidly growing global seismic networks, have produced a vast amount of high-quality data. These new data allow us to develop new techniques to determine the coupling and splitting characteristics of multiplets, and hence determine the 3-D structure of the Earth. Current techniques tend to be computationally intensive and non-linear and require detailed models of earthquake sources (which might be unavailable for the large and often complicated events used in free-oscillation research). Here, we introduce a new technique that allows us to solve for the most general form of the splitting matrix in a few steps without knowledge of the earthquake sources. The method takes advantage of the fact that certain linear combinations of seismograms for a single earthquake have an autoregressive property for which the propagator matrixis relatedto theexponentiated splitting matrix.To retrievethepropagator matrix,it is necessary to use only displacement scalars from a reference earth model and instrument calibrations to perform a two-step linear inversion. Multiple events can (and, generally, must) be used to allow retrieval of the propagator matrix. It is straightforward to recover the splitting matrix from the propagator matrix and it is the elements of the splitting matrix that provide linear constraints on the 3-D structure of the earth. We illustrate the technique by using nearly 900 vertical-component recordings from 10 large earthquakes to recover the splitting matrices of a variety of multiplets. The results are presented as splitting functions, including some of the ¢rst robust anelastic splitting functions to be determined.