2.4. Observed ship behavior and track by ECDIS
The ship׳s behavior in the coordinate system of Fig. 1, which is in horizontal and in time series of sway, surge and yaw, has been calculated and transformed by using the observed data of the ship׳s ECDIS (Electronic Chart Display and Information System), which recorded the ship׳s position and heading every 10 s during the initial strike of the tsunami. Fig. 4 shows the observed VLCC׳s behavior during the tsunami.