SPATIAL VARIATION AND ITS STOCHASTIC MODELING OF SEISMIC GROUND MOTIONS IN HARD SOIL BASED ON THREE-DIMENSIONAL-DENSE-ARRAY STRONG-MOTION OBSERVATION RECORDS

Abstract

This study used strong-motion records from the three-dimensional-dense-array observation network at the Hamaoka Nuclear Power Plant to evaluate the spatial variation (coherency and variation in Fourier amplitude ratio between points) of seismic motion in hard soil. The evaluated spatial variation characteristics of seismic motion were used to derive statistical models based on regression analysis. The results showed that coherency decreased with increasing frequency and distance. Meanwhile, variation in Fourier amplitude ratio increased with increasing frequency and distance below 5 Hz.