Fig. 12
From: Estimation of phase velocity using array observation of microtremors with arbitrary shape
Comparisons of estimated phase velocities obtained through DSPAC method with those through conventional methods (synthetic data). The array shape is the most-flattened triangle (R1-R6-R7), except for “FK (6 RCVRs)”. Although the SPAC method is not applicable to this array shape, two cases of “SPAC” are applied without or with the limited conditions of azimuthal averaging. The FK and CCA methods do not work so well in almost any frequency range and higher ranges, respectively. The incoherent noise affects the results in the lower frequency range. As a result, reasonable results are obtained for a very limited range of frequency by the CCA method. To avoid spatial aliasing in the analysis of the FK method, we searched over a limited range of phase velocities, which resulted in the misalignment with the target value in the frequency range above 12 Hz.