Depth Coherency Analysis for Strong Seismic Motions from KiK-Net: Fid-Bau Portal

Depth Coherency Analysis for Strong Seismic Motions from KiK-Net

Chen, Qingjun / Hong, Na

Due to the limited number of seismic records in the soil and inefficient use of one-dimensional wave theory in the estimation of vertical components for seismic waves, this paper studies depth coherency (coherency between the surface seismic waves and that at depth) in order to describe seismic acceleration at different depths based on surface seismic acceleration signals. In this study, the authors utilized data from the KiK network to investigate the variability of seismic ground motions with depth and obtain a model to simulate coherency of depth-dependent ground motions. Furthermore, by using the methodology described in the Chinese Code for the Seismic Design of Buildings, the authors categorized a number of test locations based on the depth and shear velocity of the soil cover. Four different types of sites were defined and both the horizontal and vertical components of ground motion from strong motion seismometers were analyzed. The results show that there is no significant dependence between the estimated coherencies from different earthquake magnitudes or epicentral distance (less than 200 km). Moreover, the behavior of depth coherency is site-dependent and there are notable differences between horizontal and vertical depth coherency. In addition, existing spatial coherency models may not provide a satisfactory estimate of the variation of depth coherency.