1997 Fiscal Year Final Research Report Summary
Structure analysis of weathered zone of bedrock slope by seismic prospecting
| Project/Area Number |
07454123
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geology
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| Research Institution | Osaka City University |
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Principal Investigator |
HIRANO Masashige Faculty of Letters Professor, Osaka City Univ., 文学部, 教授 (00047177)
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| Co-Investigator(Kenkyū-buntansha) |
MITAMURA Muneki Faculty of Science Assosiate Professor Osaka City Univ., 理学部, 助教授 (00183632)
ISHII Takayuki Department of Education, Professor, Osaka Education Univ., 教育学部, 教授 (40045159)
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| Project Period (FY) |
1995 – 1997
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| Keywords | no-vegetation slope / seismic prospecting / surface velocity / mirage phenomenon / potential of sediment yield |
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| Research Abstract |
A particular landform is associated with a definite surface material produced under a balance of weathering to erosion, where a vegetation plays an important role. Destruction of the vegetation covering mountain slope often brings a serious envionmental problem concerning the run-off and sediment yield associated with the change of hydrological situation. From this point of view, the nature of surface materials exposing on bedrock slopes at the east of Himeji City and the Ashio Mountain have been investigated, based on the data by seismic prospecting. The refraction data showed that the slope with the inclination of 35 to 42 degrees have been underlain by the layr with the P-wave velocity of 800-1200 m/sec. The surface layr shows mirage phenomenon commonly on vegetation-covered and bedrock slopes, and this fact together with the critical velocity given above gives the estimation of the maximum loss of weathered material of ca. 10m thick at the ridge part covered with vegetation. The average depth of material loss for a wedge pinching from ridge to vally head is estimated ca. 5m, and this gives the potential of sediment yield by destruction of vegetation cover form slopes under humid climate.
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