Development of short-period strong motion prediction method considering medium heterogeneity and application for great subduction zone earthquakes

自2003年枥木地震以来，长周期强震一直是人们关注的焦点。然而，在俯冲带大地震中，短周期的强震运动也会很大，因此短周期的构造会受到破坏。为此，我们提出了一种先进的统计格林函数方法来更准确地预测短周期强运动。在震源效应方面，本文提出了一种基于强震预测配方，通过添加限制条件反演特征震源模型的方法，并将该方法应用于2005年福冈西部地震和2005年宫根县地震。我们还考虑了震源模型中各振幅的非均质性，并对假设的南开地震进行了宽带强运动预测。对于路径效应，我们建立了一个基于散射理论的包络模型来引入介质非均质性对短周期强运动的影响。然后将该方法应用于宫根崎地震和南开地震的强震预报。此外，利用预测的南开地震强震震源，预测了普通木结构房屋和低层钢筋混凝土房屋等短周期结构的建筑损失率和环境负荷。上述强运动是横波的水平分量。在本研究中，我们扩展了统计格林函数方法，以便合理地预测纵波和横波的水平分量和垂直分量的强运动。我们还开发了P波和S波水平和垂直分量的经验衰减关系，以验证格林函数或预测强运动。

Long-period strong motions have been in the spotlight since the 2003 Tokachi-oki earthquake. During great subduction-zone earthquakes, however, short-period strong motions would be also big and so short-period structures would be damaged. Therefore we develop an advanced statistical Green's function method to predict short-period strong motions more accurately. For source effects, we develop a method to invert a characterized source model by adding restrictions based on so-called strong motion prediction recipe and apply the method to the 2005 west off Fukuoka prefecture earth-quake and the 2005 Miyagiken-oki earthquake. We also consider the heterogeneity in each asperity of the source model and predict broadband strong motions for hypothesized Nankai earthquake. For path effects, we construct an envelope model based on a scattering theory to introduce the effects of medium heterogeneity into short-period strong motions.Then we apply the developed method to strong motion prediction for hypothesized Miyagiken-oki earthquake and Nankai earthquake. In addition we predict building damage ratio of short-period structures such as ordinary wooden houses and low-rise rein-forced-concrete buildings and environmental burden using predicted strong motions for the Nankai earthquake.Strong motions mentioned above are horizontal components for S-wave. In this study we extend the statistical Green's function method in order to reasonably predict strong motions of both horizontal and vertical components for both P and S waves. We also develop empirical attenuation relations of both horizontal and vertical components for both P and S waves to verify the Green's functions or predicted strong motions.