著者

神谷 泉 小荒井 衛 関口 辰夫 佐藤 浩 中埜 貴元 岩橋 純子

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.122, no.5, pp.854-874, 2013-10-25 (Released:2013-10-31)

参考文献数

31

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SAR interferometry is widely used for dense measurements of surface displacements caused by earthquakes, but the method cannot be applied if displacements are too large. The near-epicentral area of the Iwate–Miyagi Nairiku Earthquake in 2008 is an inapplicable case. Therefore, we applied photogrammetry to measure surface displacement caused by the earthquake. The maximum horizontal and vertical displacements were found to be 5.3 m and 2.9 m, respectively. We recognized three lines where displacement changes abruptly. The displacement distribution is like that of a reverse fault along the first line (A–B), an east-rising fault along the second line (F–G–H; west of line A–B), and a left-lateral fault along the third line (B–C; between line A–B and line F–G–H). The earthquake source fault reaches or approaches the ground surface at line A–B, with slippage decreasing toward the ground surface. The fault-like large surface deformation found north of the Aratozawa Dam is on the first line. The fault-like deformation was caused by the motion of the earthquake source fault, and the relative displacement of the fault-like deformation was enlarged by local causes. A gravitational mass movement found north of the fault-like deformation is one cause. Because the width of the rising area is small, only 3.5 km, at the southwestern side of line B–C, the slip of the earthquake source fault is mainly distributed near the ground. Line F–G–H suggests the existence of a geological structure that causes the abrupt changes of vertical displacement without a horizontal displacement, for example a high-angle fault.  We assumed: (1) the slip on the main fault is distributed only in a shallow area at the southern part of the main fault and only in a deep area at the northern part; and, (2) the difference of slip caused two lateral faults between southern and northern parts. The assumption qualitatively explains many observation results, such as why there is an abrupt change of horizontal displacement along line B–C and why line F–G–H has a convex part to the east. We found a correlation between the occurrence of large landslides and abrupt changes of displacement, in other words large surface strain. The following mechanisms are possible causes of the correlation: (1) stress from surface strain increased large landslides; (2) faults (not only the main fault) may exist under the focused areas, rupture of faults caused both large surface strain and large seismic motion, and seismic motion induced large land slides. We also found that landslides and slope failures occurred densely over the slipping area on the main fault, based on the assumptions in the previous paragraph. Because photogrammetric measurements need interactive observations, we could avoid observations on possible embanking areas. Because photogrammetry allows intensive measurements at interesting areas, we revealed a two flexure-like distribution of vertical displacement. Therefore, photogrammetry is an effective method for measuring surface displacement caused by an earthquake.

著者

岩橋 純子 安藤 明伸 西岡 芳晴 川畑 大作 白石 喬久

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.131, no.4, pp.463-472, 2022-08-25 (Released:2022-09-08)

参考文献数

19

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A system was created using an exploration-type computer game as the basic material, and its educational effects were verified with the aim of stimulating the interest of students of the digital native generation in the local history of the region. Research classes were conducted using Minecraft (Mojang/Microsoft) teaching materials at Miyagi University of Education Junior High School in Sendai City. The theme of the classes was to convey knowledge about the geology and geological history of the region. Teaching materials were created for students to learn about geological formations in the Kamisugi area of Sendai City, including the region of their junior high school, with the aim of deepening their interest in local geological history and their understanding of the changing earth. A Minecraft world was used with underground strata that reflected information from a geological boring survey conducted in the past at the school, school buildings, and teleportable landscapes of past geological eras, and questions were asked on knowledge of geology based on school textbooks or research papers. The following were confirmed from the research classes at the junior high school. The game using a familiar school as a setting was very popular among the students, and they were not bored by the knowledge questions. The key words of the geological era that the students reached were frequently mentioned in the questionnaire given after the classes. The game is considered to be effective for helping students to understand and remember things visually, while having an enjoyable and positive experience.

著者

岩橋 純子 山岸 宏光 神谷 泉 佐藤 浩

出版者

The Japan Landslide Society

雑誌

日本地すべり学会誌 : 地すべり = Journal of the Japan Landslide Society : landslides (ISSN:13483986)

巻号頁・発行日

vol.45, no.1, pp.1-12, 2008-05-25

参考文献数

39

被引用文献数

7 8

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2004年 (平成16年) 7月の新潟豪雨および10月の新潟県中越地震によって, 傾斜5度以上の丘陵地・山地に相当する中新世~更新世堆積岩類の斜面で起きた崩壊について, 25mグリッドのレベルで, 傾斜, 雨量, 最大加速度, 地質, 曲率, 地質構造, 斜面方位のGISデータを用いて判別分析を行った。判別分析によって, 各パラメータの崩壊に対する寄与を評価した。その結果, 傾斜は重要なファクターであるが, 豪雨による斜面崩壊では, 傾斜以上に日雨量の寄与が大きいこと, 西山階泥岩優勢タービダイト層と魚沼層では豪雨と地震に於ける崩れやすさが異なっていたこと, 曲率の寄与は豪雨で大きいこと, 地質と地質構造の寄与は地震で起きた大崩壊の場合大きいこと, 斜面方位の寄与には地域差があることなどが分かった。

著者

中埜 貴元 遠藤 涼 大野 裕幸 岩橋 純子

出版者

公益社団法人 日本地理学会

雑誌

日本地理学会発表要旨集 2019年度日本地理学会秋季学術大会

巻号頁・発行日

pp.51, 2019 (Released:2019-09-24)

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河川氾濫による浸水域を夜間に把握するためのセンサの調査と河川水域を対象とした性能試験を実施した.夜間観測に有効なセンサとして超高感度カメラと熱赤外線カメラを選定し,冬季夜間に試験を実施した.その結果,超高感度カメラで水域が判別できるとともに,最適ISO感度は51200〜102400程度であること,熱赤外線カメラではある程度水域が識別できるものの,温度閾値などでの抽出は困難であることなどが分かった.