Journal of the Japan Society of Engineering Geology
Online ISSN : 1884-0973
Print ISSN : 0286-7737
ISSN-L : 0286-7737
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Volume 56, Issue 5
Displaying 1-4 of 4 articles from this issue
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General Article
  • Prediction of Potential Sites of Deep-Seated Catastrophic Landslides and its Future Research
    Masahiro CHIGIRA
    2015 Volume 56 Issue 5 Pages 200-209
    Published: December 10, 2015
    Released on J-STAGE: January 23, 2016
    DOIhttps://doi.org/10.5110/jjseg.56.200
    JOURNAL FREE ACCESS
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    Deep-seated catastrophic landslides （DCLs） accompany very rapid movement and long runout, causing severe damage. In order to mitigate the disaster induced by such landslides, prediction of their potential site is firstly indispensable. This paper summarizes geological and geomorphological features of DCLs on the basis of case studies and evaluates their probability of occurrence with a scope of future study on that issue. Rain-induced DCLs are generally preceded by deep-seated gravitational slope deformation （DGSD）, so DGSD types and geomorphological features, such as small scarps upslope and failures downslope, were used to evaluate the probability of DCL occurrence into four ratings. DCLs induced by earthquakes have several preparatory processes: chemical weathering, DGSD, and undercutting of a landslide once collided to the opposite slope. In a rare case, some landslides are induced by water gashing out from the ground during an earthquake. Prospective researches on DCL includes characteristics of DGSD destabilized by earthquakes, dynamic behavior of halloysite-rich soil, which commonly forms a sliding layer of earthquake-induced DCLs, velocity dependence of shear strengths of soils and rocks, evaluation of destabilization of a slope by water filtration in connection with high-resolution rainfall monitoring.
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Original Article
  • Typology on Gravitational Slope Deformation based on Geomorphic Analysis using LiDAR-DEM
    Tomoyuki TAKAMI
    2015 Volume 56 Issue 5 Pages 210-218
    Published: December 10, 2015
    Released on J-STAGE: January 23, 2016
    DOIhttps://doi.org/10.5110/jjseg.56.210
    JOURNAL FREE ACCESS
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    Gravitational slope deformation is closely related to deep-seated landslides, loosening, and slope failure on excavation. Gravitational deformation in mountainous region has been surveyed by the aerial photo interpretation. It is pointed out on the basis of the unique terrain such as double ridge and uphill-facing small scarps. Recently the airborne laser scanner has been developed, and it has become possible to grasp the micro-topography of such deformed slopes. Topographic feature of slope deformation is defined in more accurate by performing the analysis of the micro-topography using　high resolution DEM compiled from airborne laser scanner. I propose a method for description of micro-topography using geomorphic images created from LiDAR-DEM. I try to estimate the mechanism of gravitational deformation by micro-topographic analysis. The area, depth, and slope stability of gravitational deformation is able to estimate from classification from combination of geological structure and micro-topography.
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  • Juvenile Landslide Landform in Rock Slope inferred from Balanced Cross-section Analysis and its Displacement Rate
    Hideki KOSAKA
    2015 Volume 56 Issue 5 Pages 219-229
    Published: December 10, 2015
    Released on J-STAGE: January 23, 2016
    DOIhttps://doi.org/10.5110/jjseg.56.219
    JOURNAL FREE ACCESS
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    This study provides a basis for landform of juvenile landslide formed from rock slope deformation. The target of rock slope type is daylighting dip, hangnail dip and infacing dip slop. One of techniques used to calculate of rock slope deformation for understanding landslide landform is that of drawing balanced cross sections. The sections suggest that gentle slope at head and toe of slope deformation is formed by the occurrence of the juvenile landslides. Measurement values of slope angle and displacement rate from rock slope deformation to juvenile landslide was affected by lithological character. These interpretations may present a basic directions for risk of civil engineering work in large-scale slope and countermeasure against rock slope deformation.
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  • Sorting out Landslide Topography in Japan by Knick Line Distribution, and Geological Signs of Landslide Occurrence
    Shinjuro KOMATA
    2015 Volume 56 Issue 5 Pages 230-238
    Published: December 10, 2015
    Released on J-STAGE: January 23, 2016
    DOIhttps://doi.org/10.5110/jjseg.56.230
    JOURNAL FREE ACCESS
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    The archipelago in Japan situates in unstable subduction zone, where earthquakes and volcanic activities frequently occur. Mountains have been continuously subjected to upheaval under the tectonically active stress since the quaternary era. Scoring and erosion frequently occur in river banks and slopes due to heavy rains and river flows, which form “knick lines” in terms of geomorphology. Slope rock mass also become fragile due to weathering in the long term. These specific geological and geomorphological conditions in Japan, in couple with wet climate conditions, induce erosion in river basins and mass movement such as landslide and failure.
    This paper describes several phenomena of erosion process including river capture in neighboring basins, and gravitational deformation of rock slopes which may indicate signs of landslides.
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