SYSTEMATIC UNDERSTANDING OF THE GROUND MOTION AMPLIFICATION ON THREE-DIMENSIONAL BASIN STRUCTURE

Abstract

 Understanding ground motion amplification in a soil profile with complex basement is important in designing the input ground motions. This study focuses on the existence of a vibration mode which relates to the vibration of the ground as a single body to understand the effect of complex soil profile on earthquake ground motions. The three-dimensional numerical analysis of a narrow sedimentary basin shows the existence of a dominant frequency which is consistent at all points irrespective of the thickness of the underlying sedimentary layer. Based on the difference of transfer function values at the dominant frequency, it is determined that the basin vibrates as a single body with a fundamental mode. In addition, the distribution of the maximum amplitude resulting from the input pulse wave containing the dominant frequency was also explained with the fundamental mode. Thus, in this study, it is observed that the effect of soil profile on ground motion amplification can be studied by modal analysis of the ground.