Study on estimation for the destruction of the moraine dam for the risk assessment on the disaster that causes glacier lake outburst flood

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About the realities of the glacial lake outburst flood (GLOF) damage, the following results were obtained ;1)Starting of GLOF is a debris flow, and a large amount of debris is sedimented a few km down the moraine dam.2)Afterwards, the flow erode the bed of valley and down a long distance over several tens km while inducing the collapse of both sides intermittently.3)At the collapse slopes caused by GLOF, its vegetation is not recovered in 20 years or more. Due to so, these slopes have been eroded intermittently for a long term. Therefore, it is necessary to consider not only the case of generation of large-scale GLOF, but also a long series of measures of the recovery of this vegetation after it is generated.About the stability of the moraine dam, the following results were obtained ;1)At the front of moraine dam, the thick moraine sediment, 60m more thick, was measured by the seismic explorations. The results clearly show that the moraine dam was been steady because its sediment acts … More as the counter weight for slide of the ice body remaining into the moraine dam.2)It was found from the result that the melting of the ice body remaining the moraine dam is important for the estimating of the stability of the moraine dam. In addition, it is necessary to observe the surroundings, slopes and hanging glacier of the glacial lake (not only dam site) by the aero photograph. These are important points for evaluating the collapse risk.And, the temperatures into the moraine dam had never be 0℃ or less through the year. On the lake water, these of every depth of the lake also be 0℃ more in winter season. Therefore, the authors pointed that the simulation of melting of the ice body is needed for the risk evaluation of GLOF, because the condition of ice body has been progressing the melt now.Finally, the authors indicate the countermeasures ;1)Somebody says that the blasting of the moraine dam is most effective for reduce the GLOF. However, the authors do not concur with such kind of opinion. At first, the blasting of the ice body is difficult due to its scale. The moraine dam is also due to its composed loose. In addition, if GLOF is generated, the erosion of the slopes is caused for a long term.2)The subsidence of ice body has been progress too slowly. So, if we can control it, it will become the effective countermeasure for GLOF. Less