著者

菅沼 悠介 石輪 健樹 川又 基人 奥野 淳一 香月 興太 板木 拓也 関 宰 金田 平太郎 松井 浩紀 羽田 裕貴 藤井 昌和 平野 大輔

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.129, no.5, pp.591-610, 2020-10-25 (Released:2020-11-13)

参考文献数

101

被引用文献数

1

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The Antarctic Ice Sheet (AIS) is one of the largest potential contributors to future sea-level changes. Recently, an acceleration of AIS volume loss through basal melting and iceberg calving has been reported based on several studies using satellite observations, including radar altimetry, interferometer, and gravity measurements. A recent model that couples ice sheet and climate dynamics and incorporates hydrofracturing mechanism of buttressing ice shelves predicts a higher sea-level rise scenario for the next 500 years. However, the calibration and reproducibility of the sea-level rise projection from these models relies on geological sea-level reconstructions of past warm intervals. This suggests that a highly reliable reconstruction of the past AIS is essential for evaluating its stability and anticipating its contribution to future sea-level rise. In particular, a relative sea-level reconstruction in East Antarctica is the key to solving the problems and refining future projections. The current understanding of sea-level change along the East Antarctic margin is reviewed, including Glacial Isostatic Adjustment (GIA) effects, and a new strategy is proposed to address this topic based on seamless sediment coring from marine to lake in the East Antarctic margin. This project will provide essential data on AIS change since the last interglacial period.

著者

菅沼 悠介 川又 基人 白水 薫 小山 拓志 土井 浩一郎 金田 平太郎 青山 雄一 早河 秀章 小花和 宏之

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.126, no.1, pp.1-24, 2017-02-25 (Released:2017-04-20)

参考文献数

36

被引用文献数

6

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Unmanned aerial vehicle-based “Structure from Motion” (UAV-SfM) photogrammetry is becoming increasingly important for obtaining high-definition topographic data in a variety of earth science research. Antarctica is one of the best fields in which UAV-SfM surveys are applied, because detailed geomorphological data are essential for reconstructing past Antarctic ice sheet changes and understanding landform evolution processes in a hyper-arid and hypothermal environment. However, application of UAVs in Antarctica has been limited because of difficulties arising from low temperatures and the restricted availability of the Global Navigation Satellite System (GNSS)-assisted navigation system at high latitudes. In this article, we provide methodological solutions for these difficulties, and report several preliminary results of UAV surveys in central Dronning Maud Land and the Soya Coast in East Antarctica. A digital elevation model (DEM) obtained in central Dronning Maud Land clearly shows 3D structures of polygons developed on glacial tills. At the Soya Coast, a DEM analysis reveals detailed geomorphological characteristics, such as moraine ridges originating from a former ice stream and differential erosion of the basement due to weathering. Based on these results, we suggest that the UAV survey has certain merits for conducting an efficient field survey in the extremely large areas of Antarctica within a limited time, and has great potential for reconstructing past Antarctic ice sheet changes and obtaining a further understanding of landform evolution processes.

著者

小嶋 智 丹羽 良太 岩本 直也 金田 平太郎 服部 克巳 小村 慶太朗 山崎 智寛 安永 一樹

出版者

Japan Society of Engineering Geology

雑誌

応用地質 (ISSN:02867737)

巻号頁・発行日

vol.63, no.1, pp.2-12, 2022-04-10 (Released:2022-06-06)

参考文献数

42

被引用文献数

1

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中部日本,越美山系,冠山地域にみられる二重山稜地形は,山体重力変形(DSGSD)により形成されたものである.二重山稜地形の間の凹地を埋積した堆積物は,上位より,(a)炭質泥層と植物遺体に富む層の互層,(b)明灰色泥層,(c)橙色礫質泥層からなる.(c)層は基盤との不整合直上の基底礫層と解釈した.(a)層に含まれる木片の加速器質量分析計を用いて測定した放射性炭素年代(AMS-14C年代)と,7,300 cal BPの鬼界アカホヤ火山灰(K-Ah)により,凹地埋積堆積物の平均堆積速度は約0.25 mm/yearであり,二重山稜地形は約11,000年以上前に形成されたと推定した.比抵抗トモグラフィー探査の結果から,この凹地は,伸びに直交する方向の断面では東に薄くなる楔形を呈し,凹地の西を限る東に急傾斜した重力性断層に沿った円弧滑りにより形成されたと推定した.約7300年前の地表面を示すK-Ahの層準は,水平で西に傾斜した基盤にアバットしている.このことはDSGSDによる二重山稜地形の形成が約7300年前までには終了し,その後は安定していることを示している.DSGSD活動は,おそらく最終氷期後の寒冷・乾燥気候から温暖・湿潤気候への変化により引き起こされた.氷河の後退とそれに伴う急斜面の形成,支えや重圧の徐荷による同様な斜面の不安定化は,世界中から報告されている.(b)層から(a)層への層相の変化も,この気候変動に伴う植生の変化に起因する可能性がある.

著者

金田 平太郎 岡田 篤正

出版者

日本活断層学会

雑誌

活断層研究 (ISSN:09181024)

巻号頁・発行日

vol.2002, no.21, pp.73-91, 2002-06-30 (Released:2012-11-13)

参考文献数

35

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Surface rupture with maximum right-lateral displacement of 150cm and length of about 1 lkm was observed during the 1943 Tottori earthquake of Mw: 7.0, which struck the eastern Tottori prefecture, southwest Japan. We compiled all the previous reports and papers regarding the surface rupture associated with the earthquake as precise location maps (Appendix 1) and a data table (Appendix 2). We also showed the slip distribution along the surface rupture (Fig.3).The trace of the 1943 surface rupture exhibited the large step and quite sinuous geometry compared with other strike-slip surface breaks. This observation probably means that the causative fault for Tottori earthquake is at the infant stage on its way of evolution based on the Wesnousky's fault evolution model (Wesnousky,1988). Most of the surface rupture during the earthquake occurred along the geomorphologically detectable active fault (Shikano-Yoshioka active fault system). Thus, we can recognize the possible surface faulting event around the epicentral area based on recent understanding of tectonic geomorpholgy. However, the length of the subsurface seismogenic fault is underestimated by the presently proposed method (Odagiri and Shimazaki,2000) and this sh ould lead to crucial underestimation of the seismic moment and also strong ground motions. The method to estimate the lengt h Df the seismogenic fault must be reestablished.

著者

金田 平太郎 岡田 篤正

出版者

Japanese Society for Active Fault Studies

雑誌

活断層研究 (ISSN:09181024)

巻号頁・発行日

vol.2002, no.21, pp.73-91, 2002

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Surface rupture with maximum right-lateral displacement of 150cm and length of about 1 lkm was observed during the 1943 Tottori earthquake of Mw: 7.0, which struck the eastern Tottori prefecture, southwest Japan. We compiled all the previous reports and papers regarding the surface rupture associated with the earthquake as precise location maps (Appendix 1) and a data table (Appendix 2). We also showed the slip distribution along the surface rupture (Fig.3).<BR>The trace of the 1943 surface rupture exhibited the large step and quite sinuous geometry compared with other strike-slip surface breaks. This observation probably means that the causative fault for Tottori earthquake is at the infant stage on its way of evolution based on the Wesnousky's fault evolution model (Wesnousky,1988). Most of the surface rupture during the earthquake occurred along the geomorphologically detectable active fault (Shikano-Yoshioka active fault system). Thus, we can recognize the possible surface faulting event around the epicentral area based on recent understanding of tectonic geomorpholgy. However, the length of the subsurface seismogenic fault is underestimated by the presently proposed method (Odagiri and Shimazaki,2000) and this sh ould lead to crucial underestimation of the seismic moment and also strong ground motions. The method to estimate the lengt h Df the seismogenic fault must be reestablished.

著者

金田 平太郎 柏原 真太郎 小村 慶太朗

出版者

海洋出版

雑誌

号外地球 = Chikyu monthly/special : カラー版 (ISSN:09169733)

巻号頁・発行日

no.69, pp.112-120, 2018