The Journal of the Geological Society of Japan
Online ISSN : 1349-9963
Print ISSN : 0016-7630
ISSN-L : 0016-7630
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Volume 114, Issue 12
Displaying 1-4 of 4 articles from this issue
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Review
  • Problems and perspectives of the tsunami deposits after the 2004 Indian Ocean tsunami
    Kazuhisa Goto, Shigehiro Fujino
    2008 Volume 114 Issue 12 Pages 599-617
    Published: December 15, 2008
    Released on J-STAGE: June 05, 2009
    DOIhttps://doi.org/10.5575/geosoc.114.599
    JOURNAL FREE ACCESS
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    Immediately following the 2004 Indian Ocean tsunami, tsunami deposits have been studied well by many research teams. Especially, influences of the tsunami at the shallow sea and intertidal zone, sedimentary characteristics of tsunami deposits on land, and erosion and preservation processes were studied well. These new knowledge would contribute to advance the studies of past and modern tsunami deposits. On the other hand, data that should have been taken immediately after the event was not obtained sufficiently due to the absence of a manual for geologists at the emergency survey. Limited survey time and research fund as well as the less communication among researchers also prevent to collect important tsunami data after the event. Moreover, there are new problems that were raised (or not clarified) from the studies of the tsunami deposits. For example, (1) unique characteristics of the tsunami deposits, (2) the relationship between the hydraulic values of tsunami and sedimentary process of tsunami deposits, and (3) sedimentary characteristics of tsunami deposits under the sea have not yet been understood well. In order to clarify these problems, corroboration and complementary study among different research fields are highly required.
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Articleds
  • Characterizing tephras by major-element analysis of glass inclusions in plagioclase phenocrysts:
    Preliminary results from the DKP tephra of Daisen Volcano, Japan
    Akira Furusawa
    2008 Volume 114 Issue 12 Pages 618-631
    Published: December 15, 2008
    Released on J-STAGE: June 05, 2009
    DOIhttps://doi.org/10.5575/geosoc.114.618
    JOURNAL FREE ACCESS
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    Distinguishing the ancient eruption products of Daisen Volcano can be difficult: the Daisen tephras are not reliably differentiated on the basis of optical or chemical tests of hornblende or orthopyroxene. Major-element analyses of volcanic glass are affected by weathering. Here I explore a new approach, based on major-element analysis of pristine glass inclusions preserved in plagioclase phenocrysts.
    Samples of three tephras (DKP, DSP, and DNP) at proximal locations near Daisen Volcano and samples of the DKP tephra from two distal locations were analyzed by energy-dispersive X-ray (EDX) techniques. Of the glass inclusions in the three Daisen tephras, only DKP is relatively homogeneous throughout each ash unit in the major-element composition (SiO2, Al2O3, FeO, CaO, and K2O) whereas both DNP and DSP differed significantly between their lower to middle parts and their upper parts. Although the DSP and DKP tephras have a slight degree of overlap, the two could be distinguished on the basis of their glass inclusions. The distal DKP tephras at Takano and Oda are shown to be correlated with the proximal DKP tephra at Daisen and distinct from the DSP tephra at Daisen.
    Major-element analysis of plagioclase-hosted glass inclusions is a promising method for investigations of weathered tephras.
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  • Interpretation of geological hazard using high-resolution optical satellite imagery:
    Comparison of interpretation characteristics of satellite images
    Mamoru Koarai, Hiroshi P. Sato, Hiroshi Une, Kazuo Amano
    2008 Volume 114 Issue 12 Pages 632-647
    Published: December 15, 2008
    Released on J-STAGE: June 05, 2009
    DOIhttps://doi.org/10.5575/geosoc.114.632
    JOURNAL FREE ACCESS
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    We analyzed large-scale geological hazards in the case of the Northern Pakistan Earthquake, the Middle Java Earthquake and the Leyte landslide, using optical high-resolution satellite imagery such as QuickBird, IKONOS, ALOS PRISM and SPOT5. The characteristics of satellite images were compared to those of disasters on the interpretation cards. It is possible to recognize large collapses using 2.5 m-resolution satellite images; however 1 m-resolution satellite images are necessary for small-scale collapses and cracks. For the recognition of building damages in the urban area, 1 m-resolution stereo images are necessary; however it is impossible by 1 m-resolution mono image. For surface earthquake faults, it is useful to combine the recognition of building heavy damaged area using 1 m-resolution satellite image, and the identification of cliff landforms using 2.5 m-resolution stereo images. In order to understand hazard conditions, it is important for satellite imagery to be not only of high resolution but also stereoscopic.
    We proposed a method for recognition of large-scale geological hazards using optical high-resolution satellite imagery.
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