| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2020: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2019: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2018: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
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| Outline of Final Research Achievements |
Arrival time differences between high- and low-frequency signals of regional P waves from earthquakes deeper than 400 km were found in not only the northeastern Japan but also Mariana and Tonga-Fiji-Kermadc islands. The observations imply the global existence of a metastable olivine wedge that is a low velocity anomaly in subducting plate. In addition, it was found by using regional P waves from a part of the deep earthquakes that 660-km seismic discontinuity, which has been considered as phase change of olivine including metastable phase, is not simple. The lower limit and location of deep earthquakes may be affected by the other characteristics than the olivine phase change.
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