著者

オガワ フミオ フクダ ヨウイチ アカマツ ジュンペイ シブヤ カズオ Fumio OGAWA Yoichi FUKUDA Junpei AKAMATSU Kazuo SHIBUYA

雑誌

Proceedings of the NIPR Symposium on Antarctic Geosciences

巻号頁・発行日

vol.4, 1990-09

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Tidal gravity observations were made at Syowa and Asuka Stations, Antarctica, by the 28th Japanese Antarctic Research Expedition (JARE-28). LaCoste & Romberg type G gravity meters were used with electrostatic feedback amplifiers. The tidal output voltage records were sampled at intervals of 30min for both stations. The data with stable drift were selected and calibrated to tidal gravity variation. The number of selected data is 2976 from April 1 to June 1,1987 for Syowa Station and is 8736 from June 2 to November 30,1987 for Asuka Station. The admittance parameters of gravity change for atmospheric pressure and temperature variations are obtained as -0.311 μgal/mbar (1 μgal/mbar=10^<-10>m^2/kg) and 0.003 μgal/℃ (1 μgal/℃=10^<-8>m/s^2℃) for Syowa Station, and -0.264μgal/mbar and 0.029μgal/℃ for Asuka Station, respectively. When we consider appropriate elastic constants of ice, the above admittance parameter of atmospheric pressure change can be explained by both the upward attraction and loading deformation of the ice sheet by air mass for an extent of 30km covering the site. δ-factors which are corrected for oceanic tidal loading effects range from 1.130 (K_1) to 1.250 (M_2) for Syowa Station, and from 1.134 (P_1) to 1.330 (K_2) for Asuka Station, respectively. For diurnal tides, there is no significant difference between the obtained δ-factors at both stations. They are consistent with the theoretical values calculated by WAHR for the 1066A earth model. For semi-diurnal tides, however, the δ-factors at both stations are 1-17% larger than the WAHR's theoretical prediction values. The δ-factors for semi-diurnal tides at Asuka Station on the ice sheet (about 1000m thick) are as a whole larger than those at Syowa Station on the bare rock of East Ongul Island in Lutzow-Holm Bay. We presume that the tidal deformation of the ice sheet may be systematically larger than the ice-free area when we interpret the obtained result, but detailed examination of the earth models including surface ice layers has to be made for accurate interpretation of the tidal gravity observation in the Antarctic region.

著者

松島 健 山下 幹也 安原 達二 堀口 浩 宮町 宏樹 戸田 茂 高田 真秀 渡邉 篤志 渋谷 和雄 Takeshi Matsushima Mikiya Yamashita Tatsuji Yasuhara Koh Horiguchi Hiroki Miyamachi Shigeru Toda Masamitsu Takada Atsushi Watanabe Kazuo Shibuya

雑誌

南極資料 = Antarctic Record (ISSN:00857289)

巻号頁・発行日

vol.47, no.3, pp.395-408, 2003-11

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南極氷床上のクレバス帯等の,地上からは到達困難な地域での人工地震観測を目的とした投下型地震観測装置(南極ペネトレータ)を開発し,第43次日本南極地域観測隊で実施する東南極みずほ高原における人工地震探査で使用するために,22本のペネトレータを昭和基地に持ち込んだ.しかし,開発の遅れに伴う国内試験の不足から種々の不具合が発生し,今回は本観測での使用をあきらめざるを得なかった.当初の目的は果たすことができなかったが,国内では得られない環境でのペネトレータ投下実験を行い,投下姿勢,着地衝撃力,温度変化等の貴重なデータを得るとともに,南極内陸部での実際のヘリコプター運用への知見を得ることができた.これらの成果はペネトレータ型地震計の改良のみならず,今後の各種投下型観測機器の開発・製作に多いに役に立つものと考えられる.

著者

サカイ リョウキ シブヤ カズオ アユカワ マサル Ryoki SAKAI Kazuo SHIBUYA Masaru AYUKAWA

雑誌

Proceedings of the NIPR Symposium on Antarctic Geosciences

巻号頁・発行日

no.4, pp.80-89, 1990-09

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A non-magnetic pillar for observation of geomagnetic field was installed at Seal Rock, East Antarctica in January 1987 by the 28th Japanese Antarctic Research Expedition. A G.S.I. (second-order) precise magnetometer was set on the pillar, and absolute measurements of the geomagnetic field were made 7 times during 19 September-18 December, 1987. The averaged values of the observed declination angle, inclination angle and the total magnetic intensity are -36°19.2' (westward), -63°53.3' (upward) and 43073nT, respectively. These observed values are consistent with the theoretical values calculated by the IGRF (1985) model.