Rock fractures along boreholes are visually described using a newly developed borehole fractures column technique. The technique uses borehole TV and core sample observation data, and its usefulness relevant to fractures cross-hole section is here exemplified through a case study of borehole core samples taken from the Grimsel Test Site (GTS), Switzerland.
 At the GTS, several fractures of mm-scale consist a fractures zone of m-scale (first order fracture zone), and the zone is identified as forming a part of much larger fractures zone (second order fractures zone of 5-10m thick). Cross hole continuity relations for each fractures order are discussed on the basis of the regional trend of fracture systems, development and continuity of the fractures zone on outcrops in test site tunnel and preferred orientation of each fracture. The second order fractures zone could be fully correlated within the distance of ca. 10m on the cross-hole section. The borehole fractures column technique could also be used to provide recommendations for in-situ permeability tests.

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 This study has revealed the geological structure of the Sone Hills fault zone and the formation process of the Sone Hills. This fault zone spans the boundary of the Kofu Basin and the Misaka Mountains in Yamanashi Prefecture, which is located in central Japan. Tectonic landforms in the hills run ENE-WSW, and reverse faults, high-angle faults, and normal faults are located along the tectonic landforms. Reverse faults extend between the basin and the hills and between the hills and the mountains. High-angle faults, normal faults, and antithetic (reverse) faults are located at crests and saddles between the reverse faults. In the Sone Hills, faulting resulted in the formation of an anticline with a crest (tectonic bulge) in the Middle Pleistocene. This crest rose further in the Late Pleistocene, forming dissected fans.

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