Strong motion and damage prediction for huge subduction-zone earthquakes based on a high precision prediction technique

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In this research, in order to develop a quantitative damage prediction technique for a great subduction-zone earthquake and to verify its validity, the following three investigations were performed :1)Analysis of a source process and the development of the strong motion prediction technique,2)Extraction of site characteristics and the construction of underground structures, and3)Model creation for quantitative damage prediction.For task no.1, the strong motion generation areas were determined for seven interplate earthquakes in Off-Tokachi and Off-Kushiro regions. Then the empirical Green's function method was used to evaluate strong motions during the next Tonankai earthquake and the validity of the method was discussed. For statistical approach, the spectrum separation technique and the time-variation characteristic modeling technique are applied to strong motion data obtained by national networks such as K-NET for a broadband period range up to 10 seconds. We used them for a large s … More ubduction-zone earthquake.For task no.2 by using collected information on geographical feature classification for Chiba City three-dimensional surface soil structure model was built, and the validity of the model was shown. As for the fundamental characteristics of strong motions in Nobi Plain, various analyses were performed on observed strong motion records. For more precise determination of an underground structure, an improved receiver function method was proposed.For task no.3 the technique how to construct a structure model based on its response characteristics obtained from microtremor or aftershock records was proposed, and its verification was carried out by comparing it with past experience. Finally strong motion and damage prediction was performed for the Nankai earthquake by using prediction technique for strong motions and for structural damage. As a result, although heavy damage will be generated by strong motions reaching seismic intensity of 7 in the source region, the predicted damage in the population concentrated areas does not seem so large as we had been afraid of. Less