| 講演要旨(和文) | | 熊本城域において15点の同時観測を実施した。M=2.7の余震記録が得られ，城内域における地震動の違いがみられた。これは，余震に含まれる周期成分が短周期に富んでおり，地盤特性周期とみられる0.6sec程度の成分を含んでいなかったからである。余震による応答スペクトルの周期および振幅特性から，５つの地盤応答特性に分類された。常時微動のH/V比からは，余震記録で卓越している周期より長周期成分が検出されている。また，PS検層が実施されているボーリング地点の常時微動の卓越周期は，検層によるS波速度による水平多層構造を仮定しての卓越周期より長く，水平構造に起因するものならば，さらに深い構造が関与しているか，あるいは3D構造が関係している可能性もある。石垣擁壁端部においては，水平方向に2倍以上の増幅が見られるが，熊本城の石積擁壁の崩壊の多くが上端部位の水平滑り出しに起因しており整合的である。 |
|
|
| | 講演要旨(英文) | | Temporal monitoring of ground motion in Kumamoto Castle at 15 points were performed in November 22, 2016. Micro-tremor was measured and aftershocks of Kumamoto Earthquake of April, 2016 were recorded. The earthquake ground motions at each site in the castle shows different ground motions. The response spectra of 15 sites of an aftershock of M2.7 were grouped into some five zones. The predominant period of H/V ratio of micro-tremor monitoring was longer than the response spectra of M2.7 record. This is due to the lack of the long period component of the aftershock of M2.7. The H/V spectral ratio at a site where a boring was performed with PS-logging was compared with predominant period for horizontally layered ground by boring with S velocity. The predominant period of micro-tremor result is longer than the estimated period for horizontally layered ground by boring with S-wave velocity. The difference may be either too shallow layer or 3D effects rather than 2D formation. Amplification at the edge of the stone masonry wall were observed over 2.0 ass expected theoretically. The amplified observation supports the concentrated damage of stone masonry wall at the depth near the top of the wall. |
|
|
|
| |
|