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| | Abstract | | Marine electric and magnetic fields are obtained at marine magnetotelluric (MT) surveys. Both of data often contain noises, which cause errors in the inferred sub-seafloor resistivity structure. The noises must be removed, however, coherent noises cannot be removed by using a conventional stacking method. A newly proposed method for geophysical data analysis, Independent Component Analysis (ICA), cannot extract the noise if the phase shift of signal (or noise) is dominant. Here, we proposed noise removal in the marine electric field with Frequency Domain Independent Component Analysis (FDICA). FDICA is the ICA to focus on the temporal change of complex spectrum of electric and magnetic fields. We apply this new method for observed marine MT data. As a result, by using FDICA, we succeeded to remove coherent noise having phase shift and extract the MT signals. The efficiency was improved greatly, and better than the conventional stacking. |
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