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Investigation of Factors Affecting the Transportability of the P/S Amplitude Ratio Discriminant

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Technical rept. 9 Jun 2001-9 Jun 2003

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The research under this program has investigated problems associated with transporting regional-phase amplitude ratios, such as PnSn or PnLg ratios. The first study investigated the effect of sensor site effects on the variance of PS ratios. Using multiple array recordings of groups of events in the same source region, we characterized the factors that contribute bias or the scatter of PS ratio measurements, after correction for propagation path effects. The variance in the PS ratio around regional arrays reveals the extent to which site affects cause variations in PS ratios. The partitioning of the variance between source, path, and receivier effects was examined by analysis of variance ANOVA. In the second study, we performed a statistical analysis of the transportability of PS ratio discriminates using separability measures and optimum transformations in order to reduce dimensionality of multiple frequency PS ratios. These transformations consist of calculating the intra-class, and inter-class scatter matrices for PS ratio discrirminants and using the eigenvectors, corresponding to the largest eigenvalues of,the inter-class matrix to compute optimum transformation of discriminants that provide the best separation. We applied this analysis to distance-corrected,discriminants in different regions e.g., China,Eurasia, North A,merica in order to compare discriminant effectiveness for different regions and to evaluate the transportability of optimum discriminant decision surfaces.

Subject Categories:

  • Statistics and Probability
  • Seismic Detection and Detectors

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