Study on relationship between strong motions and structural damage observed during the West off Fukuoka Prefecture earthquake

2005年3月20日，福冈县西外海发生7.0级地震，这是自1995年兵库县南部大地震以来，在大城市附近发生的第一次7级地震。我们发现：1)对K-Net、Kik-Net、JMA台网、福冈县台网等地的地震记录进行了收集和分析。然后，我们描绘了沿断层面的滑动(地震矩)的不均匀分布。我们在震中东南部发现了一个单一的凹凸体(一个强烈的斑块)，从这个凹凸体辐射出来的强烈运动被沿着凯戈断层东侧的厚厚的第四纪地层放大。2)在市中心进行了广泛的建筑物破坏调查，掌握了结构类型、层数和施工年限的破坏统计数据。我们还调查了其他类型的破坏，如人身伤害、室内破坏、液化破坏和山体滑坡。我们发现，凯戈断裂东侧的建筑物损伤率较大，且较老的建筑物损坏较严重。我们还认为，室内破坏与楼层数有很强的相关性。值得注意的是，损伤主要发生在非结构构件中，这可能有助于防止主要结构构件的进一步损伤。3)通过将假定的张拉运动与观测到的损伤进行比较，考察了非线性响应分析模型的适用性。通过使用兵库县南部地震期间的破坏建立的模型，我们认为，计算的破坏比率比观测到的要大得多，因此我们可能需要调整我们的预测模型，以适应中等严重的输入

The West off Fukuoka Prefecture earthquake of Magnitude 7.0 occurred on March 20, 2005, which was the first earthquake of M7 class occurred near a big city since the devastating Hyogo-ken Nanbu earthquake of 1995. It is possible to obtain a lot of observational data that bears statistical analysis.We found:1) The seismic records of K-NET, KiK-net, the JMA network, and Fukuoka Prefecture network and others were collected and analyzed. We then delineate a heterogeneous distribution of slip (seismic moment) along the fault plane. We found a single asperity (a strong patch) located in the southeast of the hypocentet The strong motions radiated from this asperity were then amplified by thick Quaternary layers along the eastern side of the Kego fault2) The extensive building damage investigation was conducted in the central part of the city, and the damage statistics fur structural types, number of stories, and construction age has been grasped. We also investigated other types of damage, such as human injury, indoor damage, damage by liquefaction, and landslides. We found that the damage ratio of buildings is larger in the eastern side of the Kego fault, and that older buildings had more serious damage. We also hind that the indoor damage depends strongly on the number of stories. We should note that the damage occurs mostly in a non-structural components, which may contribute to prevent further damage in the major structural components.3) By comparing a presumed strung motions with observation damage, we investigated applicability of the nonlinear response analysis model. By using the model established by the damage during the Hyogo-ken Nanbu earthquake, we hind that calculated damage ratios are tuned out to be much more than the observed and so we may need to tune up our prediction model for a moderately severe input