2024-03-28T11:49:59Z
https://repository.dl.itc.u-tokyo.ac.jp/oai
oai:repository.dl.itc.u-tokyo.ac.jp:00033024
2022-12-19T04:08:41Z
80:4535:4817:4821
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Continuous Observation of Earth Resistivity by Means of the Electrical Well Logging Method in a Bore Hole near the Yamasaki Fault
観測井を利用した山崎断層の比抵抗連続観測
吉野, 登志男
128755
行武, 毅
128756
453
application/pdf
The electrical well logging method has been applied for continuously measuring the earth resistivity. Both the current and the potential electrodes have been installed in an observation bore hole drilled very close to the Yamasaki fault in Hyogo prefecture. Electric currents of a rectangular wave form of an amplitude of 10 mA with a period of 10 second are being applied between the current electrodes and the apparent resistivity is computed from the potential difference measured between the adjacent potential electrodes. It was found that the apparent resistivity had increased about 10% between March and September, 1980. After that it gradually decreased. Superposed on this gradual change are small fluctuations closely related to changes in the water level in the bore hore. An examination of these short period fluctuations indicates that the apparent resistivity increases about 0.7 % for a one meter rise in water level with a time lag of 8 hours. On the other hand, the gradual increase of 10% in the resistivity observed between March and September is supposed to be a part of the seasonal variations. It was found that this change could be well correlated to the seasonal change in strain observed by an extensometer installed in the direction of N56°E in a tunnel across the Yamasaki fault about 10 m from the bore hole. Although the bore hole used for this experiment is only 20 m deep, the present technique will be applicable in deeper wells to measure the resistivity of the deeper crust.
departmental bulletin paper
東京大学地震研究所
1982-01-08
application/pdf
東京大學地震研究所彙報 = Bulletin of the Earthquake Research Institute, University of Tokyo
3
56
603
621
AN00162258
00408972
https://repository.dl.itc.u-tokyo.ac.jp/record/33024/files/ji0563010.pdf
jpn