Poster

[NS-P-02] Simulation of microtremor exploration using 3D finite difference method to study the effect of velocity anomaly on the observed phase velocity

*Haruhiko Suzuki¹, Koichi Hayashi¹, Chisato Konishi¹ (1. OYO (Japan))

We performed a simulation of microtremor exploration using three-dimensional finite difference method to study the effect of the cavities and concrete structure in underground. A subsurface structural model including the cavity and concrete structure with a horizontal direction of 550m and a vertical direction of 180m was created. The vertical grid size is 1m from the surface to the depth of 70m, and 2 m from the depth of 70 m to 180 m. The sources of the microtremors were placed on the circumference of a circle with a radius of 250m from the center of model. The peak frequency of the source spectra was set to 2Hz and random phase was given. The effect of the velocity structure anomaly appeared on the phase velocity when the depth of the velocity anomaly was similar to the size of the cavity or concrete structure.