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Study on prediction of long period ground motions on sedimentary basins in Southwest Japan for huge subduction-zone

日本西南部巨大俯冲带沉积盆地长周期地震动预测研究

基本信息

批准号：
18310123
负责人：
IWATA Tomotaka
金额：
$ 8.86万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18310123/
关键词：
Nankai earthquake long-period ground motions prediction of strong ground motions sedimentary basin Oita basin Osaka basin source model basin velocity structure model

项目摘要

We studied long-period ground motions (>2seconds) in large sedimentary basins of South-Western Japan during huge subduction earthquakes. In the first year, we analyzed nation-wide strong motion network data to find sites that have long-period ground motion characteristics. In the South-Western Japan area, the Osaka and Oita basins could generate long-period ground motions. For the Osaka basin, there are plural underground velocity structure models for ground motion prediction. We validated the models by simulating ground motions for the 2004 Kii-Hanto-Toho-Oki event. Peak periods of observed ground motions can be explained by the simulations within 10%. For the Oita basin, there are few underground information and we conducted microtremor observations to estimate basin structures. We constructed underground velocity structure model for the Oita basin and confirmed the model by reproducing ground motions at Oita station for the 2000 Tottori earthquake.Based on those analyses, we conducted long-period ground motion prediction for next hypothetical Nankai earthquake and compared the long-period ground motion characteristics. We pointed out that large long-period ground motions could attack both basin area during the next Nankai earthquake, especially for the Oita basin for the first time. We also developed the effect of source rupture scenarios of the events. For the Oita basin, ground motion levels would be changed between the source model of the East hypocenter model and that of the West hypocenter model.

我们研究了日本西南部大型沉积盆地在巨大俯冲地震期间的长周期地面运动（> 2s）。在第一年，我们分析了全国范围内的强震台网数据，以寻找具有长周期地面运动特征的场地。在日本西南部地区，大坂和大分盆地可能产生长周期地震动。对于大坂盆地，有多种地下速度结构模型用于地震动预测。我们通过模拟2004年Kii-Hanto-Toho-Oki事件的地面运动来验证模型。观测到的地震动峰值周期可以解释的模拟在10%以内。对于大分盆地，地下信息很少，我们进行了微动观测，以估计盆地结构。我们构建了大分盆地的地下速度结构模型，并通过再现2000年鸟取地震时大分台的地震动来验证该模型，在此基础上，对下一次假设的南海地震进行了长周期地震动预测，并比较了长周期地震动的特征。我们指出，大的长周期地面运动可能会在未来的南海地震袭击两个盆地地区，特别是大分盆地的第一次。我们还开发了事件的源破裂情景的影响。对于大分盆地而言，东、西两种震源模型的地震动水平会发生变化。