Imaging strategies to interpret 3-D noisy audio-magnetotelluric data acquired in Gyeongju, South Korea: data processing and inversion
Imaging strategies to interpret 3-D noisy audio-magnetotelluric data acquired in Gyeongju, South Korea: data processing and inversion
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DOI：
10.1093/gji/ggab002
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发表时间：
2021-02
影响因子：
2.8
通讯作者：
J. Uhm;Jun Heo;D. Min;Seokhoon Oh;Hojoon Chung
中科院分区：
文献类型：
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作者：
J. Uhm;Jun Heo;D. Min;Seokhoon Oh;Hojoon Chung
2016年9月12日，韩国庆州发生了有记录以来最大的地震。从那时起，人们就要求了解庆州地震震中附近的地质结构。作为了解震中周围地质结构的初步步骤，进行了三维音频大地电磁（AMT）调查。通过数据处理和反演，对这些三维AMT数据进行成像。然而，由于在庆州获得的AMT数据非常嘈杂，传统的成像程序没有产生可靠的结果。为了获得一个可靠的模型从这样的噪声数据反演，我们提出了各种成像策略：一个额外的数据处理技术，使用传统的数据处理后的Nyquist图和几个反演策略相关的数据的选择，数据的加权，模型参数向量和拉格朗日乘子用于正则化的约束。通过应用额外的数据处理步骤和几种反演策略，我们能够成功地反演有噪声的现场数据。反演结果表明，应用奈奎斯特图的数据筛选程序显着改善的结果相比，只使用常规的数据处理。在这种情况下，研究中提出的成像策略可以用于成像噪声MT/AMT字段数据为其他地区。
The largest earthquake recorded in South Korea occurred in Gyeongju on 2016 September 12. Since then, understanding the geological structures near the Gyeongju earthquake's epicentre has been demanded. As a preliminary step to understand the geological structures around the epicentre, a 3-D audio-magnetotelluric (AMT) survey was conducted. These 3-D AMT data were imaged through data processing and inversion. However, because the AMT data acquired in Gyeongju were very noisy, conventional imaging procedures did not yield reliable results. To obtain a reliable model inverted from such noisy data, we propose various imaging strategies: an additional data processing technique using the Nyquist diagram after conventional data processing and several inversion strategies related to the selection of data, the weighting of the data, the constraints on the model parameter vector and the Lagrange multiplier used for the regularization. By applying the additional data processing step and several inversion strategies, we were able to successfully invert the noisy field data. The inversion results verify that the data-screening procedure applying the Nyquist diagram remarkably improves the results compared with those obtained using only conventional data processing. The imaging strategies proposed in this case study can be used to image noisy MT/AMT field data for other regions.