| 講演要旨(和文) | | 地熱地域や山岳地域では平坦地が少ないため、高い観測点密度でのAMT探査は困難である。そこで、短い基線長での電場測定によるAMT探査を試みた。本講演では、超短基線AMT探査と通常の基線長でのAMT探査の結果を比較した。さらに多地点での超短基線AMT探査の結果から、スタティックシフトの度合いを見積もた。以上の結果から、超短基線AMT探査は実施可能であると結論付けられた。 |
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| | 講演要旨(英文) | | High-density magnetotelluric (MT) surveys, with station separation less than 100m, are rarely done in geothermal areas. It is due to less availability of enough wide-flat spaces for MT measurements. In this study, we tried audio-frequency MT (AMT) survey with electric dipole length less than 1m. We compared two AMT responses: the ultra-short-baseline AMT (USB-AMT), and the conventional AMT exploration with 15m dipoles for electric-field measurements. The results indicated a pretty good correspondence between two responses. Although the inferred errors were larger in the USB-AMT, the error levels are acceptable in the modeling of resistivity structure by inversion procedures. In addition, the degree of static shift in case of the USB-AMT was discussed. We infer that the static shift levels were less than a decade, similar to the conventional AMT explorations. In conclusion, the proposed USB-AMT is valid and can produce the MT responses with enough good quality. The USB-AMT method is available at narrow spaces: therefore, it allows us high-density AMT surveys. |
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