2019 Volume 72 Pages 17-24
We applied seismic interferometry analysis to linear array records of microtremors observed with eleven three-component seismometers in order to aim to develop a new method for exploring shallow two dimensional S wave velocity structures using short period microtremors. As a result, in the stacked cross correlation analysis, it was possible to confirm characteristic phases propagating in all directions of NS, EW and UD as a result of arranging seismometers at equal intervals in the linear array. In estimating the group velocities, the signal to noise ratios (SNRs) were particularly low in the NS direction, and it was difficult to estimate correct group velocities. On the other hand, in the EW and UD directions, it was shown that the frequency range where the SNR is higher than 10 is wide. Moreover, since it was close to the value calculated from the existing model, it is considered that a reasonable group velocity could be estimated. As a result of displaying the group velocity obtained in all combinations in two dimensions, it became clear that the group velocity slightly changed in the horizontal direction at high frequencies.