著者

岡田 篤正 渡辺 満久 佐藤 比呂志 全 明純 曹 華龍 金 性均 田 正秀 池 憲哲 尾池 和夫

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.103, no.2, pp.111-126, 1994-04-25 (Released:2010-10-13)

参考文献数

51

被引用文献数

12 38

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Many distinct lineaments have been recognized by Landsat images in Korean Peninsula. The Yangsan fault system situated in the southeastern part of Korea is especially linear, continuously traceable for a long distance (about 200km), and particularly remarkable among these lineaments. The topographic expression of the Yangsan fault system is derived from the straightly stretching fault valley with wide shattered zones in the direction of NNE-SSW. This fault system extends for about 200km from the mouth of the Nagdong River west of Busan in the south to Yeondong in the north, and geologically separates Korean Peninsula from the Japan Sea. The amount of horizontal displacement may reach 30km. It is recognized as one of the most important faults in Korean Peninsula.From the interpretations of aerial photographs, and field surveys along the central part of the Yangsan fault system, the main results are summarized as follows:1. The Yangsan fault system has repeatedly moved in the late Quaternary. The lower to higher river terrace surfaces on this system show cumulative vertical offsets.2. The vertical component is upthrown on the east side from considering the terrace offset and the distribution of the mountainous lands. This vertical movement is reverse to the topographical situation on the meso-scale.3. The fault trace is extremely straight. The fault plane is almost vertical. The shatteredzone exceeds tens of meters in width with a remarkable fault gouge.4. The longer axis of flat clasts within the gravel observed in excavated the exploratory trench showed the re-arrangement along the fault. The predominantly right-lateral movements were recognized as the elongation of clayey parts and breccias in the fault gouge.5. From these characteristics, the Yangsan fault was clarified to be active with predominantly right-lateral movement. Estimated ages of terraces and its deposits give average rates of vertical and right slip on the Yangsan fault system at about 0.02-0.03mm/y, and at least 0.05-0.1mm/y, respectively.6. The fault topography is not found on the lower and lowest terraces. As the surface of the terrace has widely been cultivated as paddy fields for long historical time, lower fault scarplets less than a few meters high might have been modified or destroyed by the human actions. Therefore, we cannot mention the existence of the younger movement on the lower and lowest terraces.

著者

中田 高 木庭 元晴 今泉 俊文 曹 華龍 松本 秀明 菅沼 健

出版者

The Association of Japanese Geographers

雑誌

地理学評論 (ISSN:00167444)

巻号頁・発行日

vol.53, no.1, pp.29-44, 1980

被引用文献数

40

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房総半島南部の完新世海成段丘は,相模トラフに沿って発生する過去の大地震に伴う地殻変動の歴史を記録している.地形的証拠および36個の¹⁴C年代測定を含む年代資料をもとに,本地域の地殻変動の量と様式について考察した.<br> その結果,本地域は, 6,150年前, 4,350年前, 2,850年前および270年前に急激な海水準の相対的低下があり,これらは,大正・元禄型地震による地震性地殻隆起によるものであると考えられる.地震間の安定期間の長さは,前回の地震時における変位量と比例関係にある.各地震直前の年代と相対的海水準高度をもとに,長期的平均隆起速度を最小二乗法を用いて求めたところ, 3.0mm/年という値が得られた.また,長期的平均隆起速度と各地震間において求められた隆起速度との値の差は,当時の海水準変動の傾向を示すものと考えられる.これによれぽ,約2,700年前ごろには海水準は低下傾向にあり,それ以降,上昇傾向にあるとみることができる.なお,同様の地殻変動様式と海水準変動の傾向は,琉球列島・喜界島の離水サンゴ礁においても認めることができた.