| 講演要旨(和文) | | 柏崎刈羽原子力発電所で得られた2019年6月18日山形県沖の地震の記録について，敷地内の空間的変動を意識して解析を行った．敷地の地質構造には褶曲が見られるが，敷地内に展開された観測点で得られた記録のフーリエスペクトルは，周波数0.5Hz以下では変動が小さく安定していた．しかし，周波数0.2Hz以下のローパスフィルター波形を用いて，時間領域で波動の伝播性状を調べると，時間帯により見かけの伝播速度・方向が異なるとともに，敷地内で伝播が一様でないことがわかった．そこで，空間的な違いを見るために，敷地全体，敷地南部の向斜部，敷地北部の背斜上，それぞれについて，f-kスペクトル解析を行った．周波数毎に得られた地震波の速度・到来方向は，ばらつきは大きいものの，微動アレイ解析による既存の地下構造の知見と整合的な傾向も見られた． |
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| | 講演要旨(英文) | | The records of the Yamagata-oki earthquake on June 18, 2019, obtained at the Kashiwazaki-Kariwa Nuclear Power Station, were analyzed with an awareness of spatial variations. Although there are folds in the geological structure of the site, the Fourier spectrum of the records obtained at the observation points deployed in the site was stable with little fluctuation at frequencies below 0.5 Hz. However, when investigating the propagation characteristics of waves in the time domain using a low-pass filter waveform with a frequency of 0.2 Hz or less, the apparent propagation speed and direction differed depending on the time and the location in the site. To investigate the spatial variation, the f-k spectrum analysis was performed on the entire site, the syncline in the southern part of the site, and the anticline in the northern part of the site. The velocity and direction of arrival obtained for each frequency varied widely, but there was a tendency consistent with the previous knowledge of underground structures. |
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