Real-Time Tsunami Prediction by Inversion Method Using Offshore Observed GPS Buoy Data: Nankaido

In Japan, the probability of a Tokai, Tonankai, and Nankai earthquake occurring in the early 21st century is high. Given this likelihood, estimating the resulting tsunami in real time is desirable. This study details an inversion method for real-time tsunami predictions using only observed offshore tsunami data. Numerical experiments demonstrate that (1) the tsunami wave source is estimated fairly well using the inversion method compared with the initial sea surface displacement calculated from the earthquake fault model; (2) the tsunami profiles are predicted with great accuracy at coastal locations of interest; and (3) the profiles are accurately and easily updated using a longer duration of observed tsunami data after an earthquake. This study also investigates techniques to improve the accuracy of the forecasts: screening optimal locations for offshore global positioning system (GPS) buoys, using a longer period of observation data, and decreasing the duration of the tsunami prediction. These techniques illustrate the practical application of this method for tsunami forecasting.