2019 Volume 29 Issue 3 Pages 181-190
Normalized Input-Output Minimization (NIOM) analysis was conducted for the earthquake records observed at Agigawa Dam in Gifu prefecture, Japan, operated by the Japan Water Agency, and the propagation velocities of the seismic waves in the dam body were closely investigated. The results revealed that (1) the S-wave velocity in the upper and the lower parts of the core zone were 420-450 m/s and 520-540 m/s, respectively, (2) the S-wave velocity in the rock zone on the upstream side was 480-500 m/s, and S-wave polarization anisotropy was found in these results, whereas (3) the S-wave velocity in the rock zone on the downstream side showed larger value (580 m/s), and the polarization anisotropy was not seen, and (4) the distributions of the P- and S-wave velocities obtained in this study were consistent with those observed by the PS logging held in 1999.