| Summary: | 南極地域での空振観測を定常的に実施するためには，省電力かつ低温環境に耐えうる空振計が必要となる．株式会社アコーと東京大学地震研究所が共同開発した新型空振計（TYPE7744N/5002A）は，既存の空振計の半分以下の消費電力を達成している．新型空振計の南極での使用について評価するため，低温環境下において極地で使用実績のある他機種との比較試験を実施した．4 機種の空振計を－30℃の実験室内で30 日間連続稼働させ，常温での試験結果と比較して振幅位相特性の変化を調べた．30 日間の稼働期間で空振計の動作に問題は生じなかった．リファレンスセンサ（Model60Vx2, Chaparral Physics）に対する振幅比は常温での結果と比較して最大19% 変化しており，空振計の感度は低温により変動すると考えられる．位相特性については低温による影響は僅かであった．今後は昭和基地で試験的に越冬観測を行うなどして，長期間の安定性を評価する試験が望まれる． For infrasound monitoring in Antarctica, there is a need for infrasound sensors with low power consumption and high resistance to low-temperature environments. A new-type infrasound sensor (TYPE7744N/5002A) manufactured by ACO Co., Ltd. (Japan) with the cooperation of the Earthquake Research Institute, the University of Tokyo, achieves less than half the power consumption of existing models. To evaluate the applicability of the new sensor to Antarctic observation, we conducted a low-temperature (－30℃) test for four types of sensors, including the new one. We compared the results to those from a room temperature (21℃) test and examined changes in amplitude-phase characteristics based on a reference sensor (Model60Vx2, Chaparral Physics), proven in use in polar regions. There were no problems in the operation of the new sensor during the 30 days of the test. Spectral power ratio to the reference sensor changed up to 19% compared to the room temperature test, suggesting that the sensitivity fluctuates with temperature. Phase characteristics were not significantly affected by low temperatures. Future trials are desired to evaluate the long-term stability of the new sensor, e.g., by conducting experimental overwintering observations at Syowa Station. departmental bulletin paper
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