高知県西川地すべり地における弾性波探査

概要

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The Nishikawa landslide in Kochi prefecture is one of representive landslides occured in the Mikabu green rocks. In order to investigata the mechanism of this landslide, geophysical investigations have been carried out. In this paper, the results of seismic prospecting are discussed. The relation between rock facies and P wave velosities measured is as follows: 1st layer: 0.3 km/s, 5 m thick, soil 2nd layer (1) : 1.0─1.5 km/s, 20m thick, soft, clastic sediment and talus deposit 2nd layer (2) : 2.2 km/s, 15 thick, soft clastic sediment and weathering part of basement rock 3rd layer: 2.7─3.2 km/s, 50m thick, weathering part of basement rock (black schist of Sambagawa southern marginal belt (2.7 km/s,) and phillitic green rock of the Mikabu green rocks (3.2 km/s) 4th layer: 4.0 km/s, basementrock The landslide in this area is closely connected with the weathering MIkabu groon rocks, because the head of the landslide exists in th e Mikabu green rocks and the sliding part occures in the clastic sediments consisting mainly of the weathering Mikabu green rocks. We must give attention to that it is quite within the bounds of possibillity that the 3rd layer flows plastically for a longtime giving a great infuluence on the 1 st and 2 nd layers and as its result this landslide has occured.
一般社団法人日本応用地質学会の論文