SEGJ Technical Conference

Comparison of estimation on phase velocity between SPAC and CCA using the microtremores measured in the Tachikawa-Fault zone

Abstract Centerless circular array (CCA) method is known to provide phase velocities in longer wavelength than that from the SPAC method. We applied the CCA method to the microtremor array measurements in the Tachikawa-Fault zone which have been already applied to the SPAC method. The phase velocities measured using the CCA method was compared to that using the SPAC method. We found that at most of the sites, there was only slight difference between the SPAC and the CCA method, probably because the largest correlation distance in the SPAC method is 1.73 times larger than that in CCA method with a triangular array. The maximum wavelength estimated from both SPAC and CCA methods are also similar. The similarity of the lowest frequency in which phase velocity can be estimated might be dependent on the noise to signal ratio of microtremors. Since we have discussed only with the microtremor arrays measured in the Tachikawa-Fault zone, this kind of discussion might be necessary to know the performance of CCA method in the various region.