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 54, Issue 5
Displaying 1-3 of 3 articles from this issue
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Original Article
  • Relations among Mode of Occurrence, Physical Properties and Slaking Properties of Andesitic Volcanic Rocks Formed by Volcanic Activity in a Submarine Environment
    Satoshi SUZUKI, Daizo ISHIYAMA
    Article type: Original Article
    2013 Volume 54 Issue 5 Pages 188-196
    Published: December 10, 2013
    Released on J-STAGE: April 16, 2014
    DOIhttps://doi.org/10.5110/jjseg.54.188
    JOURNAL FREE ACCESS
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     Areas in which andesitic volcanic rocks have been formed by volcanic activity in a submarine environment are distributed from Hokkaido to southwestern Japan (Sanin Province) along the Sea of Japan (so-called green tuff region). Rock collapses and tunnel deformations often occur in these areas. The mode of occurrence, characteristics of smectite, pore-size distribution and slaking properties of andesitic volcanic rocks distributed in the middle part of Akita Prefecture were studied to clarify the causes of rock collapses and tunnel deformations.
     In the rocks that show strong slaking properties, the distance between plagioclase crystals is large and the interstices between the crystals are filled with smectite. The rocks also contain large amounts of pores having diameters from 500 nm to about 10,000 nm. The rocks having the characteristics presented above are rocks consisting of the rim of a pillow lobe, matrix of pyroclastic rocks and volcaniclastic rocks having textures in which boundaries between the fragments and matrix are obscure. It is thought that slaking properties of andesitic volcanic rocks formed by submarine volcanic activity are controlled by the quantity of smectite, style of distribution of minerals (distance between plagioclase crystals) and pore distribution. Focusing on the mode of occurrence and physical properties of diagenetically altered andesitic volcanic rocks formed in a submarine environment is important for preventing disasters from the point of view of applied geology.
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Report
  • Determination of Groundwater Salinization by VLF and VES Methods in a Tsunami Inundated Coastal Plain
    Kazushi MORI, Nobuyuki OKANIWA, Tomoo HASHIMOTO
    Article type: Report
    2013 Volume 54 Issue 5 Pages 197-203
    Published: December 10, 2013
    Released on J-STAGE: April 16, 2014
    DOIhttps://doi.org/10.5110/jjseg.54.197
    JOURNAL FREE ACCESS
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     Groundwater salinization was investigated by VLF and VES methods for the coastal plain in Watari-gun, Miyagi Prefecture, which was inundated widely by tsunami flood caused by the 2011 off the Pacific Coast of Tohoku Earthquake.
     Investigation by VLF method revealed that the availability of shallow groundwater adequate for agricultural use is restricted to the western part of the plain.
     VES investigation made it clear that the low resistivity zone under 50 ohm meter has deeply invaded from shoreline to the central part of the plain. And it is estimated that the distribution of the fresh deep groundwater as an alternative water resources is limited in the western part of the plain as well as usable shallow groundwater.
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