Simulation of spatially varying seafloor ground motions with random seawater layer and complex terrain

The seismic response of ocean structures would be overestimated if the ground motions recorded at land stations are used without corrections. Considering the effect of soft soil layer and soil saturation with site transfer function, a new method was presented for studied the effect of seawater layer on vertical in-plane motions base on a simple model of Crouse and Quilter. The simulate theory of spatially varying ground motions was proposed to consider the influence of seawater layer and soil saturation of seafloor soil layer. Compared with different site conditions, four unique locate sites with the same spatial distance were chose, and two cases of with seawater and without seawater were studied. The comparison results show that the seafloor vertical in-plane motions are noticeable attenuation under seawater layer. The saturation soft soil layer has more influence on seafloor vertical in-plane motions than seawater. Due to considering the complex submarine topography, the synthesized seafloor ground motions can be applied on numerical simulation in most seafloor seismic hazard analyses.