ABSTRACT
Japan. It is revealed that the intensities of seafloor vertical motions are much lower than the corresponding onshore vertical motions and the vertical-to-horizontal (V/H) spectral ratios of seafloor motions are anomalously lower than those of the onshore motions, especially at short periods. Crouse & Quilter (1991) derived a simple transfer function model to calculate the ratio of the vertical response at a seafloor site to that at a site without the overlying seawater layer. It is found that the seafloor vertical motions could be significantly suppressed near the resonant frequencies of seismic P-wave propagating in seawater. However, although the characteristic differences between the onshore and seafloor seismic motions have been highlighted, very limited techniques regarding the simulation of seafloor seismic motions can be found in the literature.
