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| | Abstract | | CCA method proposed by Cho et al.2006 and Tada et al.2007 has shown a big advantage for the estimation of velocity to the depth related with seismic risk of structures by using a very small array. The performance of CCA was checked using 6 components array of 6m radius in comparison with 15 components SPAC using maximum radius about 100m, the simulated microtremor records N101 of Cornou et al.2006. CCA dispersion curve showed a good coincidence with that of SPAC. Both have phase velocity between the fundamental and the 1st higher mode. Considering on the poor condition in the developing countries where only one digital recorder of three components is available by luck, the applicability of CCA to this difficulty was checked. 2 sets of 3 components records selected at every 120 degrees showed the lower limit frequency about 1.4 times higher than that of 6 components CCA and a systematic lags at higher frequencies but opposite sense for different sets. To combine them, the ratio of the sum of Gz0z0 to that of Gz1z1 is used as CCA coefficient. The dispersion curve showed a good coincidence with 6 components CCA and SPAC but the limit frequency is remained un-improved. |
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