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

自2003年东京地震以来，长周期的强烈运动一直是聚光灯下的焦点。然而，在大俯冲带地震中，短周期的强震也会很大，因此短周期的结构就会遭到破坏。因此，我们发展了一种改进的统计格林函数方法来更准确地预报短周期强震。对于震源效应，我们发展了一种基于所谓的强震预报配方通过添加约束来反演特征震源模型的方法，并将该方法应用于2005年福冈县以西的地震和2005年宫城县的地震。我们还考虑了震源模型各凹凸体的非均质性，并对假想的南开地震进行了宽带强震预报。对于路径效应，我们构建了一个基于散射理论的包络模型，将介质非均质性的影响引入到短周期强震中，并将该方法应用于假想的宫城县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，预测了普通木结构和低层钢筋混凝土结构等短周期结构的房屋损伤率和环境负荷。上述强震是S波的水平分量。在这项研究中，我们扩展了统计格林函数方法，以便合理地预报P波和S波的水平和垂直分量的强震。我们还建立了P波和S波的水平分量和垂直分量的经验衰减关系，以验证格林函数或预测强震。

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.