| 講演要旨(和文) | | 近年、人工電磁/電気信号源を用いた海洋探査への注目が高まっている。本研究ではその中で、1次元海底直流法の数値計算に着目した。海底直流法は海底下浅部の比抵抗構造、例えば断層、地下水、熱水鉱床等の探査手法として有効であると考えられており、任意電極配置における1次元構造の電位計算は予測応答の評価において重要である。さらに、有効な測定配置や機器仕様の選定、あるいは2・3次元モデリングへの組み込みにおいても重要な役割を担う。我々はSato(2000)を参考にリニアフィルタ法による任意電極配置計算コードを実装し、孔井テストモデルや海底直流法を想定した種々の電極配置における応答計算に適用した。計算結果から、作成したコードは高精度に1次元応答を計算可能であり、海洋・海底直流法の電位計算に利用可能であることがわかった。 |
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| | 講演要旨(英文) | | In recent years, there has been a growing interest in offshore exploration methods that use controlled electromagnetic, EM, and/or electric sources. One such method for offshore exploration is the seafloor/marine direct-current, DC, method. In this study, we have focused on the numerical modeling of 1D seafloor DC electric potential. Seafloor DC survey is the method of choice for surveying shallow subbottom targets such as fault structures, ground water conditions, and seafloor hydrothermal deposits in coastal and deep-water areas. It is important to calculate the 1D response of arbitrary electrode configurations in order to evaluate the predicted marine and seafloor DC responses. Moreover, it is also important to develop effective survey and equipment designs and incorporate them with 2D/3D forward modeling. We have developed a new modeling code for marine and seafloor DC exploration using the arbitrary electrodes configuration based on Sato,2000, and the linear filtering method. This code has been tested using synthetic examples such as borehole resistivity logging benchmark model and seafloor Schlumberger and dipole-dipole configurations. From the results of the study, we conclude that the code is able to compute the 1D response with high accuracy, therefore, it can be used in 1D marine and seafloor DC electric potential calculations. |
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