Japan-France Joint Project on Strong Motion Prediction

1995年坂神淡路地震后，人们强烈地重新认识到对发生在人口密集城市下的活动断层上的强震进行精确预报的必要性。日本和法国都有许多活动断层，如何用理论和半经验方法预测内陆地震时的强震是本次日法合作项目的目的。为了检验强震预测方法的有效性，我们共享了1995年兵库县南部（科比）地震的强震数据库，这是一个既有强震记录，又有震源和地下结构模型的最完整的数据集。我们还分享了部署在足良谷、钏路地区（日本）和沃尔维谷（欧洲地震局，希腊）的几个密集强震动网络。利用相同的数据，我们尝试了几种方法进行强运动预测（实际上是事后预测），比较了这些结果，讨论了这些方法的应用能力和局限性。作为预测方法，我们使用了理论方法（波场的完全数值模拟）和半经验方法（经验绿色函数方法）。为了估计场地效应，我们比较了几种方法，如传统的谱比，微动数据分析等，1997年1月，我们在法国格勒诺布尔举行了一个小型的研讨会，关于强地震动的预测。我们和许多关心这项研究的研究人员参加了会议，并介绍了他们的工作，并一起讨论，以取得共识的强地面运动预测现在详细和我们将在这里，在未来的发展方向。我们做了两年来的工作报告和与会者写的简短报告。

After the Hanshin-Awaji disaster in 1995, we strongly re-recognized the necessity of the precise prediction of strong motions by earthquakes occurred active faults beneath the high-populated cities. There are many numbers of active faults both in Japan and France, and the aim of this Japan-France joint project is how to predict strong motions during inland earthquakes both of theorctical and semi-empirical methods. To check the validity of strong motion prediction methos, we share the strong motion database about the 1995 Hyogoken-Nanbu (Kobe) earthquake, which is one of the most complete data set about not only strong motion records but source and underground structure models. We also shared several dense strong motion networks deployed at Ashigara valley, Kushiro area (Japan), and Volvi valley (EUROSEISTEST,Greece). Using those same data, we tried strong motion predictions (actually, post-diction) by several methods, compared those results, discussed about the ability and limitations of applications of those methods. As the prediction methods, we used the theoretical method (complete numerical simulations of wavefields), and semi-empirical method (empirical Green function method). To estimate site effects, we compare several methods such as traditional spectral ratio, microtremor data analysis, etc.On January, 1997, we had a small symposium about the prediction of strong ground motions at Grenoble, France. We and many rescarchers conceming to this study attended and presented their works and discuss together to get the consensus of the strong ground motion prediction now in detail and where we will go from here in the future. We made the reports which contain our works for two years and the brief report which the attendance wrote down.