詳細検索結果
以下の条件での結果を表示する: 検索条件を変更
発行年: 1998年~1998年
論文タイトル: 滋賀
OR 論文タイトル: 最新活動
OR 論文タイトル: 柳ケ瀬断層
AND 著者名: 吉岡
2件中 1-2の結果を表示しています
  • ―滋賀県余呉町椿坂峠におけるトレンチ発掘調査―
    吉岡
    敏和, 杉山 雄一, 細矢 卓志, 逸見 健一郎, 渡辺 俊一, 田中 英幸
    地震 第2輯
    1998年 51 巻 3 号 281-289
    発行日: 1998/12/25
    公開日: 2010/03/11
    ジャーナル フリー
    The Yanagase fault is a left-lateral strike-slip active fault trending N-S to NNW-SSE in northern Shiga Prefecture and Fukui Prefecture. We excavated seven trenches, namely N, Ma, Mb, Mc, Md, Ms and S trenches, near the Tsubakizaka Pass along the fault in order to know the timing of recent faulting events. An almost vertical fault plane is clearly observed on the walls of the Md, Ms and S trenches. The fault cuts the AT tephra layer (about 25ka) and is covered by the K-Ah tephra layer (about 7ka) in the S trench. According to the radiocarbon dates of samples from the trench walls, the timing of the latest faulting of the northern part of the fault is estimated to be 7000 to 7200 years ago. The previous trench study on this fault at about 4km south of this trench site, indicated that the fault ruptured about 600 years ago. This difference in the timing of the last faulting event may mean that the Yanagase fault is devided into at least two segments.
  • 吉岡
    敏和, 苅谷 愛彦, 七山 太, 岡田 篤正, 竹村 恵二
    地震 第2輯
    1998年 51 巻 1 号 83-97
    発行日: 1998/07/03
    公開日: 2010/03/11
    ジャーナル フリー
    The Hanaore fault is a right-lateral strike-slip active fault about 48km long in central Japan. We carried out comprehensive surveys including trench excavations on the Hanaore fault to evaluate the seismic risk of the highly populated area, such as Kyoto City, along this fault. Three trenches were excavated on the fault. On the exposure of the northernmost Tochudani trench, a fault cutting fluvial sediments and humic soil beds appeared. The youngest age of displaced sediments is 460±60 14C yBP, and the sediments covering the fault is 360±60 14C yBP. This faulting event may be correlated to the historical 1662 Kambun earthquake. The southernmost Imadegawa trench was excavated on the road in the urban area of Kyoto City. A thrust fault cutting humic soil with pottery fragments of the Late Jomon period (about 3, 500 years ago) was observed on the trench walls. It was difficult to detect the age of the last faulting event due to lack of younger sediments and artificial modifications of the surficial materials. However, the southern part of the fault might not move during the 1662 earthquake because the damage in this area was much less than in along the northern and middle part of the fault. The historical documents recorded that the land along the Mikata fault which is located at the north of the Hanaore fault was uplifted, and the land along the western shoreline of Lake Biwa where is the east of the Hanaore fault was subsided during the 1662 earthquake. This means that the 1662 earthquake might be a multi-segment event caused by these three faults, the Mikata fault, the northern part of the Hanaore fault, and the faults along the western shoreline of Lake Biwa.
feedback
Top