**Acknowledgements**

*Earthquakes - From Tectonics to Buildings*

interpolated *FMR* and *AMR* in this figure, the interpolated corrections still make

*Modified hSAF (*HSAFmod*) by using* FMR *and* AMR *after interpolation (without using these four site) in comparison with observed hSAF (*HSAFobs*) extracted by GIT and 1D theoretical hSAF (*HSAFthe*) from the velocity structure taken from UVM at the same sites in Figures 1, 4 and 5. The values of* FMR *and* AMR *by* 

In order to evaluate an equivalent 1D S-wave site amplification factor at an arbitrary point, we propose an empirical method of correction on to the theoretical site amplification factor calculated from the unified velocity model of NIED for the Kanto and Tokai regions where the shallower- and deeper parts of the velocity structure are combined. First, we check how well the current unified velocity model in Japan can reproduce horizontal site amplification factors derived from the observed strong motions in the form of the equivalent 1D S-wave theoretical transfer functions at the nearest grid of every 250 m. The observed site amplification factors were obtained by GIT relative to the reference spectra extracted as the outcrop motions on the seismological bedrock. To be consistent with these observed site amplification factors, the theoretical transfer functions are calculated relative to the outcrop motions (twice of the input) on the seismological bedrock. We find that at about one-half of the sites the calculated 1D amplification factors show more or less acceptable fit to the observed ones, however, they tend to underestimate the observed amplifications in general. Therefore, we propose a simple, empirical method to fill the gap between the observed site amplification factors and the calculated ones based on the frequency and amplitude modification

theoretical hSAF closer to the observed hSAF.

*interpolation for each site are shown in the upper-right corner.*

**6. Conclusions**

**Figure 15.**

**136**

This study has used the strong-motion observation records from the K-NET and KiK-net of the National Research Institute for Earth Science and Disaster Resilience (doi: 10.17598/NIED.0004) as well as the seismic intensity (Shindokei) network of the Japan Meteorological Agency (https://www.jma.go.jp/jma/indexe. html, last accessed November 2020). A part of this study was supported by the Japan Society for the Promotion of Science (JSPS) Kakenhi Grant-in-Aid for Basic Research (B) Number 19H02405. Continuous support from Hanshin Consultants Co., Ltd. is highly appreciated.
