Behavior of seismic waves in the newly developed cut-down and fill-in grounds

The seismic safety was examined of ground in Japan's Tama district, where the Tokyo metropolitan government was razing hills and filling in valleys, preparing the site for urban development. Three boreholes were dug in one razed and two filled areas in order to examine the soil conditions and to perform P- and SH-wave well shootings. Q-values and shear wave velocities are compared for the sand layers and loam fills of different sites. Results are used to assume the underground structure models of these areas and to compute the waveforms at the surface where an SH pulse was vertically incident using the finite element method. Results of the study and analysis are described.