18:15 〜 19:30
[SSS23-P04] 宮城県北部の建物被害データを用いた2011年東北地方太平洋沖地震の建物被害関数
キーワード：建物被害曲線, 微動H/Vスペクトル比, 地下速度構造, 地震動の代表性
Damage ratios in subdistricts of Osaki and Kurihara cities, northern of Miyagi Prefecture are obtained from the damage data provided by the local City Offices. Ground motions in these subdistricts are estimated by use of source model proposed by Kurahashi and Irikura (BSSA, 2013) and underground velocity structures identified from microtremor H/V spectral ratios. The estimated ground motion indices (PGA, PGV, IJMA, and SI) are used to relate with the damage ratios to construct the fragility curves. It is found that the correlation in small subdistricts is improved, compared with that between the observed ground motion indices and corresponding damage ratios in a wider district.
In addition, we have added some microtremor measurement at plural sites inside each subdistrict, such as Furukawa, and Tajiri, in order to assess the representativeness of ground motions estimated at only one site for the entire subdistrict. We conducted such measurement at or near the preliminary schools inside the subdistricts. The ground motions during the mainshock are estimated with the identified velocity structures from the microtremor H/V spectra ratios. It is found that the variability of ground motions in the Furukawa subdistrict is relatively small. It suggests that the ground motions used for the fragility curves are representative for the entire subdistrict. In contrast, the variability of ground motions in Tajiri is relatively large. It may be caused by the limited numbers of preliminary schools with similar amplification factors.
In addition, we have added some microtremor measurement at plural sites inside each subdistrict, such as Furukawa, and Tajiri, in order to assess the representativeness of ground motions estimated at only one site for the entire subdistrict. We conducted such measurement at or near the preliminary schools inside the subdistricts. The ground motions during the mainshock are estimated with the identified velocity structures from the microtremor H/V spectra ratios. It is found that the variability of ground motions in the Furukawa subdistrict is relatively small. It suggests that the ground motions used for the fragility curves are representative for the entire subdistrict. In contrast, the variability of ground motions in Tajiri is relatively large. It may be caused by the limited numbers of preliminary schools with similar amplification factors.