| Project/Area Number |
16500643
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geography
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| Research Institution | The University of Tokyo |
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Principal Investigator |
SUGAI Toshihiko The University of Tokyo, Graduate School of Frontier Sciences, Professor, 大学院新領域創成科学研究科, 教授 (90251321)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2006: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2004: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | EARTHQUAKE / ACTIVE FAULT / YORO FAULT SYTEM / FUKAYA FAULT SYSTEM / PALEOSEISMOLOGY / NOBI BASIN / AYASEGAWA FAULT / KUWANA FAULT / 四日市断層 / 沖積平野 / 活動履歴 / 活断雄 / 地形 / 活動間隔 / 災害予測 / 養老断層 / 相対海面変化曲線 / 完新世 / 堆積速度 / 巨大イベント / 関東平野 |
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| Research Abstract |
Two typical reverse fault systems, the Yoro and the Fukaya fault system, and their surrounded areas were selected. Sediment coring and intensive 14C dating for the sediments coupled with geomorphological investigation revealed the following results.
1. Yoro fault system composed of Yoro, Kuwana and Yokkaichi fault, has produced a large earthquake of Mw=8.0 repetitively during Holocene.
2. The earthquake history shows an average recurrence interval of about 1000 years with a standard deviation of around 300 years.
3. Timing of the faulting events of Kuwana and Yokkaichi fault are almost the same during the middle to late Holocene and Yoro, Kuwana and Yokkaichi fault displaced at around 1586 A.D.( Tensyo-historical earthquake) and 745 A.D. (Tenpyo-historical earthquake). This indicates that Yoro fault system is a single behavior segment during the Holocene.
4. Nobi tectonic basin located in the downthrown side of the Yoro fault system has been subsided and filled with fluvial sediments rapidly during the Holocene with a high ratio of around 2mm/y. The flood sediments may remain the subsidence history. Especially comparison among the relative sea level curves reconstructed from core sediments for each individual coring site has potential to reconstruct the tectonic deformation over the basin.
5. Fukaya fault system is composed of Haruna, Takasaki, Fukaya, and Ayasegawa fault. The paleoseismological study revealed Ayasegawa fault is different behavioral segment with much lower activity from the other part of the system.
6. Long term activity of the fault shown by the subsurface geology is in agreement with the late Pleistocene faulting history. Ground penetrating radar survey coupled with arrayed coring is strong tool to clear the subsurface geology and its tectonic deformation in urbanized areas.
7. Relation between the huge scale sediment transport event and earthquake, whether the event was triggered by earthquakes should be studied.
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