In general, earthquake motion experienced by a navigable vessel is called a sea shock (or seaquake). Sea shock is assumed that the vertical ground motion of the sea floor propagates as a compressional (longitudinal) wave in water.
Seaquakes are sudden, unexpected phenomena that are induced by undersea earthquakes. There are almost no examples of their systematic measurement and the phenomenon of seaquakes is said to not be thoroughly understood.
The effect of seaquakes was studied theoretically during the 1990s, during research on the wave response of structures for the construction of VLFS. However, There are a few experimental studies on the effect of seaquakes on floating bodies because of the problem of reproducibility.
We measured ship motion caused by sea shocks by examining seabed oscillation. Such measurements provided very valuable data. The conclusions obtained in the present study are that ship motion caused by sea shocks has high-frequency oscillation. In particular, the acceleration in the z direction is remarkable.