砂留（江戸時代の砂防堰堤）の堆砂面に整備された堂々公園において常時微動測定を実施し，そのH/Vスペクトル比から公園直下の地下構造を推定した．柔らかい表層は公園中央部を流れる堂々川周辺で厚く，山の斜面に近づくほど薄くなる傾向がみられた．また，堂々川の上流側へ向かうほど，表層が薄くなる傾向も認められた．本研究で推定された地下構造は，砂留が構築される前の谷間地形を反映しており，常時微動測定は局所的で複雑な地下構造を推定する際にも有効な手段であると考えられる．

I performed the microtremor measurements on the sedimentation of Sunadome (a debris barrier in the Edo period) at Dodo park, and estimated the underground structure beneath the park by using the H/V spectral ratio. The soft surface layer was estimated to be thicker around the Dodo river flowing in the middle of the park and to be thinner nearby the mountain slope. There is also a tendency that the surface layer becomes thinner toward the upstream side of the river.These underground structures estimated in this study show the geography of the valley that existed before the construc-tion of the Sunadome. It is considered that a microtremor measurement is an effective method to estimate a locally complicated underground structure.