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| | Abstract | | On July 9, 2014, Nashi-zawa Sabo Dam was damaged by a huge debris flow. It swept away the upper part of the left bank dam body, and caused distinct dislocation of the body particularly at the lower part of the left bank. It is essential to delineate the distribution of internal fractures for the deep understanding of collapsed process. However, visual inspection only provides surface information. Whereas geophysical surveying has been rarely applied to the investigation of sabo dams, it might play an important role for the identification of the internal fractures. Therefore we tested high-resolution seismic survey using piezoelectric type accelerometers. Prestack kirchhoff time migration was adopted to enhance reflected and diffracted events recorded in the obtained data. As a result, clear events indicating internal fractures were clearly reconstructed. Additional data processing is needful to improve the spatial resolution of fractures inside the dam body. |
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