| Budget Amount *help |
¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Fiscal Year 2016: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2015: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2014: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
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| Outline of Final Research Achievements |
This study suggests that the seismic wave speeds in the mantle wedge beneath the Seto Inland Sea, western Japan, where deep low-frequency earthquakes/tremor occur, can be lower than the values previously suggested. When the mantle wedge has low speeds of P and S waves, travel time tomography using first arrivals of P and S waves would estimate the values of the speeds to be higher than the true ones. The presence of velocity discontinuities around the mantle wedge (e.g., oceanic Moho) would affect the estimates. Using arrival times of later phases can help to correct the estimates, however, a problem about how to set velocity discontinuities arises.
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