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| | Abstract | | The Rayleigh wave excited in the ground consists of several modes and the strength of each mode is decided by the characteristics of the ground and the source. Therefore the phase velocity estimated from array observation of microtremor can be considered as that of a compound mode, which is influenced by array layout and analysis method. Based on this concept, we proposed a multi-mode inversion method that takes the medium response, incident wave and array layout into account. The key thought is that, instead of calculating theoretical phase velocity while doing inversion, this method generates pseudo-observation data and estimates phase velocity from it using the same algorithm as for real data. Because the above process ensures that the two sets of phase velocity have the same properties, the misfit between them could only arise from the misfit of the models. We applied this method to a re-analysis of past data. Though an analysis with the conventional method in the past did not work well, structure model estimated by this method agrees very well with drilling data. |
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