Article
Geosciences, Multidisciplinary
Piyoosh Jaysaval, Judith L. Robinson, Timothy C. Johnson
Summary: Stratigraphic units can affect the fate and transport of subsurface contaminants within groundwater. Airborne electromagnetic methods provide information on subsurface stratigraphic features, helping to improve the understanding of geological conceptual models.
JOURNAL OF APPLIED GEOPHYSICS
(2021)
Article
Geochemistry & Geophysics
Ji Cai, Pritam Yogeshwar, Wiebke Moerbe, Maria Smirnova, Amir Haroon, Michael Becken, Buelent Tezkan
Summary: Various electromagnetic techniques have been developed for exploring natural resources. This study focuses on the frequency-domain semi-airborne controlled source electromagnetic (semi-AEM) method, which combines ground and airborne techniques to survey the subsurface down to approximately 1000 m. The study presents a 2-D joint inversion algorithm to interpret semi-AEM data together with information from long-offset transient electromagnetics (LOTEM) data. The results show that the two methods have complementary subsurface resolution capabilities, but there are discrepancies between individual and joint inversion results due to different measurement configurations, components, and error weighting of the data sets. Synthetic modelling studies suggest that flexible land-based configurations with sparse receiver locations can be combined with semi-AEM without significant loss of target resolution.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geosciences, Multidisciplinary
Hiromasa Ishikawa, Shunsuke Nogami, Masashi Endo, David Sunwall, Jurriaan Feijth, Jackie Hope, Takuji Mouri, Gen Nakamoto
Summary: Multiple geophysical techniques have been utilized for geothermal exploration in the Teshikaga area, with the three-dimensional inversion of AGG data providing detailed interpretation of subsurface features. The integrated interpretation of electromagnetic and magnetic data revealed potential geothermal reservoir areas, while the magnetic data also suggested magnetite degradation possibly caused by hydrothermal activities.
NATURAL RESOURCES RESEARCH
(2021)
Article
Geochemistry & Geophysics
Xin Huang, Colin G. Farquharson, Changchun Yin, Liangjun Yan, Xiaoyue Cao, Bo Zhang
Summary: The spectral-element (SE) method, based on the Galerkin technique, is gradually being implemented in geophysical electromagnetic (EM) 3D simulation, providing accuracy and efficiency for airborne EM forward modeling. By adapting the conventional SE method, small-scale conductivity variations and complex boundaries in realistic earth models can be better handled, allowing for the use of a coarse mesh.
Article
Environmental Sciences
S. Kang, R. Knight, T. Greene, C. Buck, G. Fogg
Summary: This study utilized AEM data to acquire high-quality data, which were inverted and transformed to obtain sediment type models and estimates of sand/gravel content. Exploring the model space revealed the large-scale structure of the aquifer system, accurately capturing and communicating the uncertainty in sediment type.
WATER RESOURCES RESEARCH
(2021)
Article
Environmental Sciences
Wouter Deleersnyder, David Dudal, Thomas Hermans
Summary: This paper proposes an appraisal tool for evaluating the inconsistency between the inversion model and multidimensional data, using a normalized gradient calculated based on multidimensional forward modeling. Additionally, an alternative approach is suggested to account for imperfect forward modeling with low computational cost. The method is demonstrated on an AEM survey, revealing potential problematic zones in the estimated fresh-saltwater interface.
Article
Engineering, Environmental
Clemens Moser, Andrew Binley, Adrian Flores Orozco
Summary: There is a growing interest in using 3D configurations in spectral induced polarization (SIP) surveys for characterizing the near-surface environment. This study investigates the enhanced resolution of SIP measurements through true 3D configurations, showing that parallel 2D collinear arrays result in artifacts and loss of resolution in the 3D structure. The findings demonstrate that 3D configurations can better resolve polarizable anomalies and provide a more accurate interpretation of waste composition and quantification of waste volume.
Article
Geochemistry & Geophysics
Saeed Nazari, Raphael Rochlitz, Thomas Guenther
Summary: For semi-airborne mineral exploration, it is crucial to design experimental procedures that can generate data to maximize desired information. Through investigating the effects of transmitter-receiver geometries for various anomalies and semi-airborne layouts, we found that a flight line spacing of 200 m and a point distance of 100 m provide the optimal trade-off between coverage and survey progress for different targets. In addition, the length of the transmitter should be at least equal to the length of the target, and the location and direction of the transmitter cables play a significant role in the inversion results.
Article
Geochemistry & Geophysics
Dana E. Peterson, Carol A. Finn, Paul A. Bedrosian
Summary: Water-saturated, hydrothermally altered rocks weaken volcanic edifices, leading to increased risk of sector collapses and mass flows of unconsolidated debris. Airborne geophysical measurements can be used to identify hydrothermally altered areas at Iliamna Volcano and suggest its instability.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geochemistry & Geophysics
Bo Zhang, Changchun Yin, Yunhe Liu, Xiuyan Ren, Vikas C. Baranwal, Bin Xiong
Summary: In this study, a new 3D AEM inversion scheme based on the finite-element method and unstructured tetrahedral local meshes was developed. Compared to traditional methods, this scheme uses irregular tetrahedral meshes to better accommodate topography and complex underground structures. The results demonstrate that the method can accurately model AEM responses and recover subsurface main resistivity structures.
Article
Chemistry, Multidisciplinary
Siyuan Sun, Changchun Yin, Xiuhe Gao
Summary: This study addresses the challenges in inversion modeling on unstructured grids and proposes a new gradient scheme and improved fuzzy c-means clustering method to effectively solve the problems and enhance model continuity.
APPLIED SCIENCES-BASEL
(2021)
Article
Geochemistry & Geophysics
Minkyu Bang, Seokmin Oh, Kyubo Noh, Soon Jee Seol, Joongmoo Byun
Summary: Conventional interpretation of airborne electromagnetic data through solving the inverse problem has limitations, while a 1D deep neural network inversion can improve accuracy. However, reliance on connecting 1D resistivity models in the final interpretation leads to lower accuracy for isolated anomalies. Therefore, a 2D interpretation technique using a recurrent neural network has been developed to overcome these limitations and consider spatial continuity.
Article
Geochemistry & Geophysics
Sihong Wu, Qinghua Huang, Li Zhao
Summary: In this study, a fast Bayesian inversion operator based on the invertible neural network (INN) is developed to fully explore the posterior distribution and quantitatively evaluate the model uncertainty. The INN effectively recovers the posterior distribution from a relatively small ensemble of predicted resistivity models and shows strong adaptability and noise robustness. The proposed INN method can support fast Bayesian inversion of AEM data and has tremendous potential for near real-time uncertainty evaluation of underground structures.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2023)
Article
Geosciences, Multidisciplinary
Duygu Kiyan, Volker Rath, Mark R. Muller, Mohammednur D. Ture, James Hodgson
Summary: Over the past decade, Geological Survey Ireland has acquired airborne electromagnetic data for the Tellus project, and developed the open-source toolbox aempy to facilitate data interpretation and modeling. Implemented in Python, aempy is adaptable for specific educational and research objectives, allowing for 1-D inversion modeling with processed frequency-domain airborne electromagnetic data.
JOURNAL OF APPLIED GEOPHYSICS
(2022)
Article
Environmental Sciences
Yuriy Davidenko, Valeriya Hallbauer-Zadorozhnaya, Ayur Bashkeev, Alexander Parshin
Summary: This article presents the results of a drone-based transient electromagnetic (TEM) survey conducted at Lake Baikal. The survey utilized an improved version of the SibGIS UAV-TEM unmanned system and a new approach to data inversion. The results demonstrate that the UAV-TEM technology can replace conventional ground-based electromagnetic surveys and provide geological structure data consistent with terrestrial measurements.
Article
Geochemistry & Geophysics
Alan Yusen Ley-Cooper, Andrea Viezzoli, Julien Guillemoteau, Giulio Vignoli, James Macnae, Leif Cox, Tim Munday
EXPLORATION GEOPHYSICS
(2015)
Editorial Material
Geochemistry & Geophysics
James Macnae
GEOPHYSICAL JOURNAL INTERNATIONAL
(2015)
Article
Geochemistry & Geophysics
James Macnae
Article
Geochemistry & Geophysics
Kate Hine, James Macnae
Article
Geochemistry & Geophysics
James Macnae
Article
Geochemistry & Geophysics
James Macnae, Kate Hine
Article
Geosciences, Multidisciplinary
James Macnae
JOURNAL OF APPLIED GEOPHYSICS
(2016)
Article
Geochemistry & Geophysics
James Macnae
Article
Geochemistry & Geophysics
Lachlan Hennessy, James Macnae
Article
Geochemistry & Geophysics
Xiuyan Ren, Changchun Yin, James Macnae, Yunhe Liu, Bo Zhang
Article
Geochemistry & Geophysics
Terence Kratzer, James Macnae
EXPLORATION GEOPHYSICS
(2014)
Article
Geosciences, Multidisciplinary
Aaron C. Davis, Raphael Dlugosch, Matthias Queitsch, James C. Macnae, Ronny Stolz, Andmike Mueller-Petke
GEOPHYSICAL RESEARCH LETTERS
(2014)
Article
Geochemistry & Geophysics
James Macnae, Xiuyan Ren, Tim Munday
Article
Geochemistry & Geophysics
James Macnae, Tim Munday, Camilla Soerensen