近江盆地南部における微動アレイ探査

Abstract

Microtremor array surveys were conducted to investigate the S-wave velocity structure at fourteen sites in the southern part of the Omi Basin around Lake Biwa. The microtremor array observation at each site consists of several triangular arrays with different radii of circumscribing circles. The phase velocity dispersion curves were obtained by analyzing the vertical components of the observed microtremors using the SPAC method. The S-wave velocity structure model was estimated by modeling the observed phase velocities using the MCMC method. The estimated bedrock depth matches the bedrock depth indicated by the reflection surveys. The information will be useful for improving three-dimensional velocity model in the Omi Basin.