Updated on 2022/12/05

写真a

 
NISHII Ryoko
 
Organization
Research Institute for Natural Hazards and Disaster Recovery Associate Professor
Title
Associate Professor
External link

Degree

  • 博士(理学) ( 2010.3   筑波大学 )

Research Interests

  • 地形学

Research Areas

  • Humanities & Social Sciences / Geography

Research History

  • Niigata University   Research Institute for Natural Hazards and Disaster Recovery   Associate Professor

    2020.4

  • Niigata University   Institute for Research Promotion Center for Transdisciplinary Research   Assistant Professor

    2019.4 - 2020.3

  • Niigata University   Institute for Research Promotion Center for Transdisciplinary Research   Specially Appointed Assistant Professor

    2017.2 - 2019.3

Professional Memberships

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Papers

  • 平成16年新潟県中越地震後に発生した地すべりの分布特性について Reviewed

    後根裕樹, 西井稜子, 石井靖雄, 櫻本智美, 藤平大

    日本地すべり学会誌   57 ( 2 )   4 - 13   2020.3

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  • 複数時期の航空レーザ測量データを用いた変動斜面末端部とすべり面発達の推定 Reviewed

    西井稜子, 石井靖雄, 佐藤匠, 本間信一

    日本地すべり学会誌   56 ( 2 )   31 - 38   2019.3

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  • Forest harvesting impacts on microclimate conditions and sediment transport activities in a humid periglacial environment Reviewed

    Imaizumi F, Nishii R, Ueno K, Kurobe K

    Hydrology and Earth System Sciences   23   155 - 170   2019.1

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  • Continuous and large sediment supply in a steep landslide scar, Southern Japanese Alps Reviewed

    Ryoko Nishii, Fumitoshi Imaizumi, Hiromu Daimaru, Wataru Murakami

    Geomorphology   312   51 - 59   2018.7

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier B.V.  

    Continuous sediment supply in the Aka-kuzure landslide scar, in the tectonically active alpine Southern Japanese Alps, was investigated using airborne light detection and ranging data in 2000, 2003, 2007 and 2012. In addition, we focused on the spatial variability of denudation patterns based on topographical analyses using DEMs. Denudation volume for the past 12 years reached about 106 m3 and mean annual denudation rate ranged from 0.25 to 0.31 m/yr. Topographical analyses revealed that sediment supply in the scar consists of a combination of two denudation types, sporadic-deep and wide-thin. These denudation types have different roles in the topographical development of the landslide scar. Sporadic-deep type supplies less volume than wide-thin type but still contributes to channel development, as it mainly occurs on lower-order streams and tends to change the convex slope into a concave slope. In contrast, although denudation depth of the wide-thin type is thin, the area affected by this type extends to the whole landslide scar. Consequently, the wide-thin type accounts for most of the total volume lost, for which detachment by frost shattering is suggested as an important role.

    DOI: 10.1016/j.geomorph.2018.04.002

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  • 地すべりのひずみ及びひずみ速度の経時変化による崩壊の切迫性評価 Reviewed

    杉井良平, 西井稜子, 石井靖雄

    日本地すべり学会誌   54 ( 6 )   259 - 268   2017.11

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    DOI: 10.3313/jls.54.259

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  • key words -18-

    NISHII Ryoko

    Journal of the Japan Landslide Society   53 ( 3 )   109 - 111   2016

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    Language:Japanese   Publisher:The Japan Landslide Society  

    DOI: 10.3313/jls.53.109

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  • Effects of deforestation and weather on diurnal frost heave processes on the steep mountain slopes in south central Japan Reviewed

    Kenichi Ueno, Kousei Kurobe, Fumitoshi Imaizumi, Ryoko Nishii

    EARTH SURFACE PROCESSES AND LANDFORMS   40 ( 15 )   2013 - 2025   2015.12

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-BLACKWELL  

    Freezing and thawing processes play an important role for the gravitational transport of surface materials on steep mountain slopes in Japan. The effects of deforestation on frost heave activity were observed through the 2012/2013 winter season in Ikawa University Forest, a southern mountainous area in central Japan (1180-1310 m above sea level). During periods without snow cover, needle ice development prevailed at a clear-cut site, and the downslope sediment movement of upper soil was 10 to 15 cm through the winter season. At a non-cut site, rise and fall in the ground surface level prevailed on a weekly scale, with no evident downslope movements at the surface; ice lens formation in the soil layer is assumed. Abrupt changes in the radiation budget, such as the strengthening of nighttime radiative cooling and increases in daytime direct insolation, induced frequent development/deformation of needle ice at the clear-cut site. In snow-free periods, the day-to-day variability in needle ice growth length and in nighttime averaged net radiation showed significant correlations; cloudy weather with warmer and moist air intrusion associated with synoptic disturbances prevented the occurrence of needle ice. Namely, day-to-day weather changes directly affected the mass movement of the upper soil after deforestation. Shallow snow cover occurred discontinuously through the winter and is likely an important factor in keeping the soil moisture sufficiently high in the upper soil layer for initiating needle ice during snow-free periods. We also discuss contributions of coastal extratropical cyclone activities providing both snow cover and cloudy weather in the southern mountain areas of central Japan to the intra-seasonal variability in frost heave and its indirect effect on soil creep and landslides on the deforested steep slopes. Copyright (c) 2015 John Wiley & Sons, Ltd.

    DOI: 10.1002/esp.3776

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  • Parallel retreat of rock slopes underlain by alternation of strata Reviewed

    Fumitoshi Imaizumi, Ryoko Nishii, Wataru Murakami, Hiromu Daimaru

    GEOMORPHOLOGY   238   27 - 36   2015.6

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER SCIENCE BV  

    Characteristic landscapes (e.g., cuesta, cliff and overhang of caprock, or stepped terrain) formed by differential erosion can be found in areas composed of variable geology exhibiting different resistances to weathering. Parallel retreat of slopes, defined as recession of slopes without changes in their topography, is sometimes observed on slopes composed of multiple strata. However, the conditions needed for such parallel retreat have not yet been sufficiently clarified. In this study, we elucidated the conditions for parallel retreat of rock slopes composed of alternating layers using a geometric method. In addition, to evaluate whether various rock slopes fulfilled the conditions for parallel retreat, we analyzed topographic data obtained from periodic measurement of rock slopes in the Aka-kuzure landslide, central Japan. Our geometric analysis of the two-dimensional slopes indicates that dip angle, slope gradient, and erosion rate are the factors that determine parallel retreat conditions. However, dip angle does not significantly affect parallel retreat conditions in the case of steep back slopes (slope gradient > 40 degrees). In contrast, dip angle is an important factor when we consider the parallel retreat conditions in dip slopes and gentler back slopes (slope gradient < 40 degrees). Geology in the Aka-kuzure landslide is complex because of faulting, folding, and toppling, but spatial distribution of the erosion rate measured by airborne LiDAR scanning and terrestrial laser scanning (TLS) roughly fulfills parallel retreat conditions. The Aka-kuzure landslide is characterized by repetition of steep sandstone cliffs and gentle shale slopes that form a stepped topography. The inherent resistance of sandstone to weathering is greater than that of shale. However, the vertical erosion rate within the sandstone was higher than that within the shale, due to direct relationship between slope gradient and vertical erosion rate in the Aka-kuzure landslide. (C) 2015 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.geomorph.2015.02.030

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  • Preliminary Study for Visualizing the Subsurface Structure of Gravitational Deformation Slopes Using Electrical Resistivity Tomography Reviewed

    NISHII Ryoko, IKEDA Atsushi

    J. Geogr.   122 ( 4 )   755 - 767   2013.8

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:Tokyo Geographical Society  

    Sackung features (scarps) have developed extensively in the Japanese Alps as a result of gravitational deformation. Electrical resistivity tomography was applied to evaluate the internal structure below eight scarps located above 2600 m a.s.l. The range of resistivity values differed significantly between the scarps and is mainly controlled by the moisture content of the ground. High- and low-resistivity areas were distinctly separated below some scarps. Areas of relatively low resistivity are considered as slightly fractured bedrock. In contrast, areas of high resistivity are likely to indicate highly fractured bedrock and/or talus without matrix. Such boundaries between high- and low-resistivity areas seem to correspond to fracture planes estimated from topography.

    DOI: 10.5026/jgeography.122.755

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    Other Link: https://jlc.jst.go.jp/DN/JALC/10023208833?from=CiNii

  • Geomorphic Dynamics and Sediment Budget in the Southern Japanese Alps: Recent Studies and Prospects Reviewed

    MATSUOKA Norikazu, IMAIZUMI Fumitoshi, NISHII Ryoko

    J. Geogr.   122 ( 4 )   591 - 614   2013.8

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Tokyo Geographical Society  

    This review paper synthesizes geomorphic dynamics, sediment transport and resulting natural hazards in mountains of the southern Japanese Alps and their drainage basins, where climatic and geological situations produce highly active landform dynamics. In alpine areas above the timber line, shallow diurnal freeze-thaw action operating in the thin topsoil produces small-scale periglacial forms, and gravitational spreading leads to numerous sackung features where snow-melt and heavy rain in places promote rockslides. In subalpine and montane areas, deep-seated landslides originate from fractured sedimentary rocks, deep V-shaped valleys, and heavy rain, while shallow landslides continue with historical forest clearance. Continuous slope failures prevent vegetation recovery and maintain debris input to valleys. Steep valleys contribute to high-density debris flows. Frequent or repetitive occurrences of these mass movements promote continuous denudation of slopes, rockfall accidents along hiking trails, and sedimentation at artificial dams. They occasionally cause significant hazards to villages further downstream. Predicting and mitigating slope hazards require distinguishing among annual, low-magnitude processes, episodic high-magnitude processes and geomorphic changes associated with long-term climate change.

    DOI: 10.5026/jgeography.122.591

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    Other Link: https://jlc.jst.go.jp/DN/JALC/10023208710?from=CiNii

  • Precursors and triggers of an alpine rockslide in Japan: the 2004 partial collapse during a snow-melting period Reviewed

    Ryoko Nishii, Norikazu Matsuoka, Hiromu Daimaru, Masatsugu Yasuda

    LANDSLIDES   10 ( 1 )   75 - 82   2013.2

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:SPRINGER HEIDELBERG  

    The Aresawa rockslide in the Japanese Alps encountered a deep, partial collapse during an early snow-melting period in May 2004, followed by further progressive movement of the headscarp area. This paper reconstructs the pre-failure topography of the Aresawa rockslide based on the analysis of aerial photographs taken in multiple periods, and analyzes the factors controlling the threshold for the 2004 collapse. At least seven months before the collapse, new tension cracks emerged about 25 m behind the headscarp as a result of downslope movement of an unstable rock slab 5-10 x 10(5) m(3) in volume, accompanied by the development of a slip plane below a pre-existing shallow trough (sackung feature). The collapse finally occurred when progressive weakening of the rock mass was combined with water infiltration into the ground during rapid snow melting.

    DOI: 10.1007/s10346-012-0353-5

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  • Kinematics of an alpine retrogressive rockslide in the Japanese Alps Reviewed

    Ryoko Nishii, Norikazu Matsuoka

    EARTH SURFACE PROCESSES AND LANDFORMS   37 ( 15 )   1641 - 1650   2012.12

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY  

    The Aresawa rockslide in the Japanese Alps experienced a partial collapse (510 x 105?m3) in 2004, followed by an accelerated downward movement of the head area rather than stabilization. This paper discusses the kinematics of a retrogressive rockslide area and factors promoting slope instability subsequent to the 2004 collapse, on the basis of geodetic surveys and meteorological observations from 2006 to 2010. The unstable area covers at least 2.3 x 104?m2 and consists of five active blocks. The main blocks are separated from the stable rock slope by pre-existing sackung features that follow the strike of the bedding plane. Shear zones below these sackung features have developed into slip planes potentially causing the next collapse. In particular, the propagation of a slip plane causing movement at 70?cm?yr-1 in the head area is promoted by bidirectional movement. It consists of slow dip-slip movement in snow-accumulating periods and rapid side-slip movement in snow-melting and snow-free periods, both of which occur on the same slip plane. This bidirectional movement appears to result from the combination of a loss of lateral support by the 2004 event and the immature state of the slip plane. The primary trigger of the acceleration in the unstable area is the stress release by the 2004 collapse. In addition, the presence of a potential slip plane below the sackung features also promotes slope instability, suggesting that sackung features behind a rockslide area may predefine the new head scarp of a forthcoming collapse. Copyright (C) 2012 John Wiley & Sons, Ltd.

    DOI: 10.1002/esp.3298

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  • 赤石山脈三峰岳周辺の岩石氷河の14C年代 Reviewed

    池田 敦, 西井稜子

    第四紀研究   50   309 - 317   2011

  • Monitoring rapid head scarp movement in an alpine rockslide Reviewed

    R. Nishii, N. Matsuoka

    ENGINEERING GEOLOGY   115 ( 1-2 )   49 - 57   2010.9

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    The Aresawa rockslide in the Japanese Alps, which partially collapsed in May 2004, produced a number of new tension cracks in the head area. This paper discusses the dynamics of the rock slope and controls on the surface velocity, based on the results of on-site monitoring of the surface movement and meteorological parameters (air and ground surface temperatures, precipitation and snow depth). The rock mass deformation progressed at ca. 60 cm yr(-1) mainly along a slip plane dipping downslope at ca. 50 degrees. The surface velocity of the slipping rock mass showed a significant seasonal variation in response to the water infiltration. The velocity was small (<= 1 mm day(-1)) in winter. Subzero air temperatures and a heat-insulating snow cover, and resulting growth of seasonal frost, prevent water infiltration into the bedrock and contribute to the rock slope stability. Most of the movement in this period is attributed to gravitational deformation originating from the overburden pressure. In contrast, the surface velocity increased (up to 10 mm day(-1)) during snow-melting and snow-free periods. Snowmelt and rainfalls promote water infiltration into the bedrock, destabilizing the rock slope and accelerating the rock slip. Such a rapid movement is attributed to water-induced sliding superimposed on gravitational deformation. (C) 2010 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.enggeo.2010.06.014

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  • The Role of Landslides in Controlling the Distribution of Linear Depressions on Granitic Mountains in the Hida Range Reviewed

    NISHII Ryoko

    J. Geogr.   118 ( 2 )   233 - 244   2009

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    Language:Japanese   Publisher:Tokyo Geographical Society  

    Linear depressions and associated uphill-facing scarps, which result from the gravitational deformation of rock slopes, have widely developed along the main ridge in the Mt. Eboshi area, northern Japanese Alps. The role of landslides in the development of linear depressions in granitic rocks is evaluated from the distribution of linear depressions, characteristics of landslides (form, magnitude and frequency) and characteristics of bedrock (geology, discontinuity, degree of weathering and rock mass strength). The morphology of landslides and changes in the areas of landslides from 1958 to 2004 are compared to the development of linear depressions. Most linear depressions lie parallel to the main ridge and the strike of major rock joints, although their distribution differs between the northern and southern areas. In the northern study area, linear depressions are concentrated on the gentle upper slopes and landslides have intensively occurred on the lower slopes. In contrast, the southern area shows sporadic occurrences of linear depressions on the middle to upper slopes and has experienced only minor landslides. The intensive occurrences of landslides and linear depressions in the northern area are considered to result basically from debuttress and stress-release caused by the landslide activity. In addition, the lower rock mass strength in the northern study area also promotes the development of linear depressions.

    DOI: 10.5026/jgeography.118.233

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    Other Link: https://jlc.jst.go.jp/DN/JALC/00330973494?from=CiNii

  • Weathering Characteristics of Granites and their Influences on Alpine Landforms in the Area of Mt. Noguchi-goro, the Northern Japanese Alps Reviewed

    NISHII Ryoko

    Transactions,Japanese Geomorphological Union   28 ( 3 )   239 - 256   2007.7

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    Weathering characteristics of two kinds of granites and their influences on landforms are compared along the main ridge of the Mt. Noguchi-goro area, the northern Japanese Alps. The two lithologies (granites A and B) contrast in the Schmidt rock hammer rebound, P-wave velocity, weathering index and physical rock properties. The granite A has lower rock strength and produces finer rock debris composed mainly of pebbles and finer materials than the granite B, reflecting the difference in the mineral composition. The granite A is subject to granular disintegration resulting from the high content of plagioclase that is sensitive to weathering. In contrast, the granite B produces a wide range of rock debris sizes from pebbles to boulders, reflecting the high content of K-feldspar that is less susceptible to granular disintegration and the predominance of macrogelivation along joints. The weathering characteristics of the two lithologies affect the types and morphology of the alpine landforms in the area, including patterned grounds, tors and mass movement features. For instance, the fine and homogeneous sizes of debris lead to the predominance of sorted stripes on slopes in the granite A area, while the wide range of debris sizes is responsible for turf-banked terraces in the granite B area. The contrasting weathering features indicate that chemical weathering plays an important role in the grain size distribution of surface materials as well as frost shattering.

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    Other Link: http://dl.ndl.go.jp/info:ndljp/pid/10807706

  • Rockfall hazard in the Daisekkei Valley, the northern Japanese Alps, on 11 august 2005 Reviewed

    Yoshihiko Kariya, Go Sato, Kuniyasu Mokudai, Jiro Komori, Masaki Ishii, Ryoko Nishii, Yosuke Miyazawa, Noriko Tsumura

    LANDSLIDES   4 ( 1 )   91 - 94   2007.3

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    This paper describes a rockfall event in the Daisekkei Valley of Mount Shirouma-dake (2,932 m), the northern Japanese Alps. The rockfall occurred on a steep cliff comprising well-jointed felsites and produced debris of >= 8,000 m(3). Most debris was deposited on an elongated snowpatch located immediately beneath the cliff, and it caused casualties among people who were trekking along a trail on the snowpatch. Additionally, a large rock block slipped 1 km on the snowpatch. The rockfall could have been due to the differential retreat of the rockwall, which contains areas of high- and low-density joints. Seasonal and diurnal freeze-thaw activities and snow avalanches and wash appear to be important factors responsible for the retreat. Although some rock blocks that can collapse further remain on the rockwall, the position of the mountain trail in the Daisekkei Valley is fixed. Fundamental reform of tourism systems for climbers, including education on natural hazards, is required.

    DOI: 10.1007/s10346-006-0067-7

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MISC

  • 地すべりのひずみ及びひずみ速度の経時変化による崩壊の切迫性評価と地すべりの崩壊事例

    藤平 大, 竹下 航, 石井靖雄, 西井稜子, 杉井良平, 森永高行

    土木研究所資料   ( 4378 )   1 - 94   2018.9

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  • 加速度センサを用いた地表傾斜計による微小な斜面変動の計測

    武田大典, 森永高行, 西井稜子, 石井靖雄

    土木技術資料   59 ( 6 )   16 - 19   2017.6

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  • 農鳥岳東面,広河内の段丘地形を構成する完新世初頭の斜面崩壊・土石流堆積物

    苅谷愛彦, 西井稜子

    地理学評論   90 ( 1 )   47 - 52   2017.1

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  • 航空レーザ測量データを用いた地すべり判読用地図の作成と判読に関する手引き(案)

    石井靖雄, 西井稜子, 武田大典

    土木研究所資料   ( 4344 )   1 - 38   2016.10

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  • 宇宙線生成核種年代測定法

    西井稜子

    地すべり学会誌   53 ( 3 )   35 - 37   2016.5

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  • Monitoring of a retrogressive rockslide in an alpine area : a case of Aresawa rockslide, Akaishi Range

    NISHII Ryoko, MATSUOKA Norikazu

    64 ( 5 )   61 - 64   2012.1

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  • レーザープロファイラーによる赤崩での土砂生産プロセスの観測

    今泉文寿, 西井稜子, 村上 亘, 宮前 崇, 小川泰浩, 大丸裕武

    中部森林研究   60   97 - 100   2012

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  • 電気探査を用いた線状凹地の内部構造推定の試み―赤石山脈アレ沢崩壊地頂部の事例―

    西井稜子, 池田 敦

    中部森林研究   59   213 - 216   2011

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  • P8. Seasonal variation of the surface velocity in the head area of the Aresawa rock slide, Akaishi Range(Fall Meeting of the Union, October 2008)

    NISHII Ryoko, MATSUOKA Norikazu

    30 ( 1 )   53 - 54   2009

  • 13. Monitoring of tension cracks in Mt. Aino, Akaishi Range

    NISHII Ryoko, MATSUOKA Norikazu, IKEDA Atsushi

    29 ( 1 )   75 - 75   2008

  • 世界最北の大学での短期集中コース「永久凍土・周氷河環境」に参加して

    西井稜子

    地形   28 ( 3 )   309 - 310   2007

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    Language:Japanese   Publisher:日本地形学連合  

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    Other Link: http://id.nii.ac.jp/1141/00110807/

  • The distribution and the origin of scarplets in Mount Mitsu-dake area, central Japan

    NISHII Ryoko

    ( 69 )   112 - 112   2006.3

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Awards

  • 日本地形学連合2018年秋季大会ベストポスター賞

    2018.11   日本地形学連合  

    西井稜子

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  • 2014年度信州フィールド科学賞

    2014.12   信州大学 理学部 信州山の環境研究センター  

    西井稜子

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  • 日本地すべり学会第53回研究発表会若手ポスター賞

    2014.8   日本地すべり学会  

    西井稜子

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Teaching Experience

  • 環境保全学特論

    2022
    Institution name:新潟大学

  • 卒業論文

    2022
    Institution name:新潟大学

  • 地質災害論

    2022
    Institution name:新潟大学

  • 自然科学総論V

    2022
    Institution name:新潟大学

  • 災害・復興科学演習及び実習

    2021
    Institution name:新潟大学

  • 斜面災害論

    2021
    Institution name:新潟大学

  • 斜面災害特論Ⅰ

    2020
    Institution name:新潟大学

  • 環境保全学特論

    2020
    Institution name:新潟大学

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