Feasibility of Using Tsunami Coda and Envelope for Forecasting Far-field Tsunami - Their Definitions and Application to 2006 Kuril Island Earthquake Tsunami -

As the first step toward forecasting the decay process of far-field tsunamis, we have introduced the concept of using "tsunami envelopes" and "tsunami codas" as measures in this paper. We applied these measures to the tsunami waveform data of the 2006 Kuril Island earthquake tsunami observed using tide gauges located in Japan. Analytical results indicate that the tsunami coda envelopes decayed exponentially with time and that the fluctuation in the nondimensional wave amplitude was interpreted by the Rayleigh distribution. Further, we found that these characteristics were commonly observed in the region facing the Pacific Ocean. Thus, the two measures can be used to reveal the characteristics of the tsunami decay process, and applying them to tsunami waveforms in realtime might realize appropriate cancelation of tsunami warnings.