Articles | Volume 10, issue 4
https://doi.org/10.5194/nhess-10-947-2010
https://doi.org/10.5194/nhess-10-947-2010
29 Apr 2010
 | 29 Apr 2010

Characteristics of abnormal large waves measured from coastal videos

J. Yoo, D.-Y. Lee, T.-M. Ha, Y.-S. Cho, and S.-B. Woo

Abstract. Recently, tsunami-like sea-level oscillations occurred in a region of the west coast of Korea (i.e. in the eastern part of the Yellow Sea), during a typical rough spring weather episode on 4 May 2008. The analysis of these tsunami-like abnormal waves focuses solely on the videos recorded by a CCTV surveillance system in the directions of the entrance and inside parts of a local coastal pocket beach. Time-series of the vertical and horizontal sea surface oscillations were extracted from the video recordings through calibrating image distortions, accumulating 1-D intensity arrays along the line transects of interest in time, and identifying the trajectories of the oscillations. Frequency and time-domain analysis of the time-series signals revealed that the maximum height of the tsunami-like waves reached 1.3 m, having a dominant period of 185 s (3.1 min). In addition, the results indicate that the celerity of the maximum height wave approximated 7.3 m/s, which lead to the losses of life of several people who could not escape immediately from the fast tsunami flooding the shore.

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