ausblenden:
Schlagwörter:
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Zusammenfassung:
A dense cabled observation network, called the seafloor observation network for earthquakes and tsunami along the Japan Trench (S-net), was installed in 2017. Since then, the tsunami forecasting methods using S-net data have been developed vigorously. Especially, tsunami assimilation techniques or waveform inversion techniques to obtain tsunami initial conditions were newly developed. However, the ocean bottom pressure data are always contaminated by non-tsunami components such as sea-bottom acceleration change, ocean acoustic wave or P wave due to the earthquake. Therefore, tsunami components are needed to be separated from those non-tsunami components before those recent tsunami forecasting methods are applied.
In this study, we developed a new tsunami forecasting method using the time average of ocean bottom pressure data (S-net). Therefore, pre-data process to eliminate non-tsunami components form original data is not necessary. To test our method, tsunamis from the various fault models distributed along the plate interface along the Japan Trench were first computed. Then, time averages of computed ocean bottom pressure data at S-net stations were calculated by changing the time average windows. Second, tsunami initial conditions, initial ocean surface deformations, were estimated using interpolation of those time averaged ocean pressure data at S-net stations. Third, forecasted tsunamis were computed from those estimated tsunami initial conditions. Finally, forecasted tsunami waveforms along the coast were compared with the tsunami waveforms computed from the fault model at first. We conclude that this tsunami forecasting method performed well in general with some underestimations of tsunami heights along the coast.
