| Budget Amount *help |
¥18,850,000 (Direct Cost: ¥14,500,000、Indirect Cost: ¥4,350,000)
Fiscal Year 2014: ¥5,460,000 (Direct Cost: ¥4,200,000、Indirect Cost: ¥1,260,000)
Fiscal Year 2013: ¥6,370,000 (Direct Cost: ¥4,900,000、Indirect Cost: ¥1,470,000)
Fiscal Year 2012: ¥7,020,000 (Direct Cost: ¥5,400,000、Indirect Cost: ¥1,620,000)
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| Outline of Final Research Achievements |
Low frequency acoustic waves, termed infrasonic waves, are excited by the sudden displacement of ground and sea surface at large earthquake (EQ) and tsunami. When the acoustic waves propagate into the ionosphere, they disturb the ionospheric plasma. The plasma disturbance has been detected by the measurement of total electron contents (TEC) between a satellite of Global Positioning Systems (GPS) and its receivers on the ground. In addition to the acoustic waves, a TEC depression lasting for a few minutes to tens of minutes, termed tsunamigenic ionospheric hole (TIH), is formed by the large EQ with tsunami above the tsunami source area. The largest TEC depression appears 10 to 20 minutes after the main shock. In this study, we show the quantitative relation between the initial tsunami height and the TEC depression rate caused by the TIH. Accordingly, the ionospheric TEC measurement is applicable to an early warning system of tsunami.
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