1586年天正地震養老断層震源説を示唆する地形地質学的記録

• 須貝 俊彦

  東京大学大学院新領域創成科学研究科自然環境学専攻

書誌事項

タイトル別名

• Geomorphological and geological records indicate that activity on the Yoro fault system caused the AD 1586 Tensho earthquake
• 1586ネン テンショウ ジシン ヨウロウ ダンソウ シンゲンセツ オ シサ スル チケイ チシツガクテキ キロク

抄録

Fault activity in the Yoro–Kuwana–Yokkaichi fault zone is considered to have been the source of the 1586 Tensho Earthquake. The Geological Survey of Japan conducted array boring and trenching surveys at Hazawa and Niwada within the ~30-km-long Yoro fault system, which is the main component of this major fault zone. This paper reports the main results of these surveys, focusing on the most recent faulting events and with new paleoseismological data.<br>At Hazawa, the boundary between prodelta and delta-front sediments formed within the Kiso River system at around 4 ka has been displaced vertically across the fault by about 15 m, and the top of the deltaic sediments formed at around 1.7 ka by ~10 m, indicating repetitive fault activity since 4 ka. The floodplain on the up-thrown side of the fault has been terraced since about the 8th century; this probably reflects the penultimate faulting event. The last event occurred after the 8^th century.<br>At Niwada, four offlapping sedimentary units separated by angular unconformities are capped by a buried soil or peat layer containing abundant plant fossils and charcoal fragments that have provided C-14 data to constrain the timing of faulting events. At least three episodes of fault activity have produced cumulative tilting during the period of stable sea level over the last 4 ka. The last two tilting events occurred after the 15^th century and around the 8^th century.<br>The most recent faulting events on the Kuwana and Yokkaichi faults occurred after the 13th century. Furthermore, the two most recent rises of relative sea-level probably reflect coseismic subsidence on the Nobi plain about 500 and 1200 years ago. It is highly likely that the Yoro–Kuwana–Yokkaichi fault zone produced both the 1586 Tensho and 745 Tenpyo earthquakes, although geological data alone is insufficient to determine the exact age of these events.

収録刊行物

• 活断層研究

  活断層研究 2011 (35), 15-28, 2011

  一般社団法人　日本活断層学会

キーワード

• 1586 年天正地震
• 745年天平地震
• 養老断層
• 桑名断層
• 四日市断層
• 群列ボーリング調査

詳細情報

• CRID: 1390001205756358656
• NII論文ID: 130005131046
• NII書誌ID: AN10157356
• DOI: 10.11462/afr.2011.35_15
• ISSN: 21865337
• ISSN: 09181024
• NDL書誌ID: 023433539
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I023433539
• 本文言語コード: ja
• データソース種別:
  • JaLC
  • NDL
  • CiNii Articles
  • KAKEN
• 抄録ライセンスフラグ: 使用不可