| 講演要旨(和文) | | VLF電波よりも安定性の高い断続波であるJJY標準電波を用いれば連続測定により2次元的に広域をマッピングすることが可能になり、測定結果の解釈の大幅な向上が見込まれる。本研究では、数値解析によりJJY標準電波の地下構造探査への有用性を検討すると共にその探査記録の特徴を評価した。電磁波の周波数はVLF帯の20kHz、JJY標準電波の40kHz、60kHzとし、各周波数の分解能、表皮深度、異常体構造の方向が探査記録に与える影響を評価した。本研究で1次磁場Hy、2次磁場Hzの偏平楕円の傾斜角の傾きを用い、地下構造探査が可能であることが示された。また、JJY標準電波はVLF電波に比べ、分解能は高いが探査深度が浅いことが示された。 |
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| | 講演要旨(英文) | | JJY standard electromagnetic wave is more stable than VLF wave, so that we can map underground structures with the date in broad area by continuous VLF method using JJY wave. The 2D records in wide area propose great advance to interpret observed resistivity distributions. In our study, we applied numerical analysis and estimated characteristics of underground responses of JJY waves to evaluate the availability of JJY standard electromagnetic wave for structural exploration as a VLF method. We used electromagnetic wave of 20 kHz as a VLF wave and 40 and 60 kHz as JJY standard electromagnetic wave and evaluated resolution performance, skin depth and influence of the geometry between an anomalous structure and a source direction at the condition of propagating electromagnetic wave of each frequency. In the results, we declare that JJY wave has enough performance to survey resistivity distribution to map the tilt of ellipse which is drawn by the amplitude and phase of primal magnetic field of Hy and second magnetic field of Hz, and the exploration using JJY wave has higher resolution performance but lower survey depth than that using VLF wave. |
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