A numerical study for relationship between coastal tsunami and bottom pressure fluctuation in the ocean generated from near-field earthquake

We investigated correlation between coastal and offshore tsunami height for our observational array of ocean-bottom pressure gauges, DONET, in the Nankai trough. But it is not easy to know correct sea surface fluctuation generated from near-field earthquakes in static bottom pressure changes. This is because the seafloor is simultaneously displaced in case of great near-field earthquakes occurred. In order to avoid the problem, we made the averaged waveforms of the absolute values of ocean-bottom pressure fluctuations during tsunami. Many tsunami calculations were executed by changing slip models on the plate interface. We checked the correlation between the average absolute of ocean bottom pressure and tsunami height at the coast. A clear correlation can be seen between the two values. This result indicates a possibility of more accurate real-time predicting of tsunami height by using arrayed ocean-bottom pressure gauge data.