Interactions of Tsunami with Natural Oscillations Implied from the 2011 Tohoku Tsunami Records Analysis Using Hilbert-Huang Transform

We have investigate the 2011 Tohoku Tsunami records in the Seto Inland Sea (SIS) in western Japan using Hilbert-Huang Transform. The SIS consists of many bays and basins such as Osaka bay and Hiuchi basin with their natural oscillation characteristics. The resulting intrinsic mode functions obtained from ensemble empirical model decomposition revealed that the tsunami propagated into the SIS interacts with natural oscillations of bays and is also affected by high tides in the SIS. During high tides, the maximum tsunami heights and arrival times are enhanced and shortened significantly from those at low tides.