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.

在巨大的俯冲地震期间，我们研究了日本西南部大型沉积盆地的长期地面运动（> 2秒）。在第一年，我们分析了全国性的强运动网络数据，以找到具有长期地面运动特征的站点。在日本西南部，大阪和OITA盆地可能会产生长期的地面运动。对于大阪盆地，有多个地下速度结构模型用于地面运动预测。我们通过模拟2004年Kii-Hanto-toho-Oki事件的地面运动来验证模型。观察到的地面运动的峰值周期可以通过10％以内的模拟来解释。对于OITA盆地，地下信息很少，我们进行了微晶体观测来估计盆地结构。我们为OITA盆地构建了地下速度结构模型，并通过在OITA站重现了2000 Tottori地震的地面运动来证实该模型。基于这些分析，我们对下一个假设的Nankai地震进行了长期周期地面运动预测，并比较了长期生长的地面运动特征。我们指出，在下一次南卡伊地震期间，大型长期地面运动可能会攻击两个盆地区域，尤其是第一次对Oita盆地。我们还开发了事件源破裂方案的影响。对于OITA盆地，地面运动水平将在东部低中心模型的源模型和西部低中心模型的源模型之间发生变化。