On the contraction of borehole at Mizuho Station, East Antarctica

• Main Authors: Tatsuo Hasemi, Akiyoshi Takahashi, Koichi Ikegami, Yoichi Tanaka
• Format: Report
• Language: English
• Published: Institute of Geo-Technology/Institute of Geo-Technology/Institute of Geo-Technology/Institute of Geo-Technology 1985
• Subjects: East Antarctica; Mizuho; Mizuho Plateau; Mizuho Station; Paterson; Antarc*; Antarctica; Memoirs of National Institute of Polar Research; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=1845; http://id.nii.ac.jp/1291/00001845/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=1845&item_no=1&attribute_id=18&file_no=1

Changes of borehole diameters at different depths down to 400m were estimated. Results are as follows : 1) Applying the flow law which was deduced from borehole closure observations by PATERSON (Rev. Geophys. Space Phys., 15,47,1977), the tertiary creep will start after about half of a year and the diameter of the hole will be 2/3 of the initial in a year and 1/10 after 2 years at a depth of 400m, provided that the shifting from the secondary to the tertiary occurs at total strain, ε=0.1. But the rate is 3 to 4 times larger when the flow law derived by MAE (J. Glaciol., 24,53,1979) from the flow observations at Mizuho Plateau is used. 2) The borehole closure rate has much difference depending on the flow law of ice. In order to induce a representative flow law of ice in Mizuho Plateau, the importance of borehole observation and technical development of boring is emphasized.