Seismic response analysis of laterally inhomogeneous ground with emphasis on strains

The objective of this paper is to make it clear how strain behaviors are affected by the lateral inhomogeneity of ground based on both theoretical simulation and array observation of earthquake motions. We use a two-dimensional pseudo-spectral method to numerically obtain strain motions as well as acceleration motions. We applied the method to some model grounds, which have typical inhomogeneity in the horizontal direction, to estimate general features of strains and accelerations. In addition, the technique was also applied to a site where subsurface irregularity is typically found and an array observation system of earthquake motions was densely deployed. In the latter application of the method, we placed emphasis on comparisons between the observed and simulated motions.