Advances of real-time tsunami detection by ocean-bottom pressure gauges

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This study aims to evolve our knowledge on the bottom pressure observed during the tsunamigenic earthquakes. At first, we evaluated the long-term sensor stability both by the laboratory experiment and the in-situ observations. And we interpreted the water pressure disturbances during the 2011 Tohoku earthquake and the following moderate-to-large aftershock by means of the time-frequency processing analysis with the ocean-bottom seismometers. As a result, the bottom pressure disturbances during the earthquake are dominated by the ocean-bottom acceleration and velocity for the intermediate frequency range and the high frequency range, respectively. In the low frequency range, on the other hand, water pressure amplitude is isolated on the bottom oscillations, suggesting that tsunami signals can be detected by using its threshold.