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
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
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
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
Geochemistry & Geophysics
Alexander Prikhodko, Andrei Bagrianski, Petr Kuzmin, Aamna Sirohey
Summary: The mineral resources exploration industry has high efficiency requirements for geophysical technologies, and airborne electromagnetic technologies have been used for subsurface exploration due to their low cost and ability to rapidly acquire data over large areas. However, limitations on the depth of investigation and technical specifications of these systems hinder their application in certain geoelectrical conditions and geographical terrains. Methods utilizing natural electromagnetic fields in the audio frequency range have significantly increased the depth of investigation and sensitivity to a wide range of resistivity contrasts.
Article
Environmental Sciences
Shengjun Liang, Siyuan Sun, Hongfei Lu
Summary: The airborne electromagnetic and magnetic surveys in Northwest China effectively identified a new gold deposit and mineralization clues, demonstrating the efficiency of the method in finding metal mineral resources.
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
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
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
Environmental Sciences
Peng Bai, Giulio Vignoli, Thomas Mejer Hansen
Summary: The study demonstrates that while using 1D forward modelling in airborne electromagnetic surveys is more computationally efficient than 3D inversions, it is important to consider the modeling error which can lead to false features in the reconstructions. Incorporating this information into the inversion process improves target reconstructions and ensures correct reliability estimates.
Article
Geochemistry & Geophysics
Roslynn B. B. King, Steven Constable
Summary: Understanding the depth of investigation is crucial for experimental design and interpretation of inversions in electromagnetic and electrical methods. While the depth of investigation for electromagnetic sounding methods has been extensively studied, the continuously towed controlled-source electromagnetic methods have been neglected. Our study demonstrates that the data density of towed electromagnetic systems at longest offset increases the depth of investigation.
GEOPHYSICAL PROSPECTING
(2023)
Article
Computer Science, Interdisciplinary Applications
Daniele Colombo, Ersan Turkoglu, Weichang Li, Diego Rovetta
Summary: The application of machine learning and deep learning in geophysical data inversion shows potential, but faces challenges such as scarcity of labeled data. Physics-informed network training helps reduce the reliance on physics models and improve the inversion process.
COMPUTERS & GEOSCIENCES
(2021)
Article
Chemistry, Multidisciplinary
Yiming He, Guoqiang Xue, Weiying Chen, Zhongbin Tian
Summary: Semi-airborne transient electromagnetics (SATEM) is a geophysical survey tool known for its ability to perform three-dimensional (3D) observations and collect high-density data in large volumes. This paper presents a new 3D model- and data-driven inversion algorithm using the particle swarm optimization (PSO) and gradient descent (GD) algorithms to improve data processing efficiency.
APPLIED SCIENCES-BASEL
(2022)
Article
Geochemistry & Geophysics
Taqi Alyousuf, Yaoguo Li
Summary: A new physics-based neural network inversion algorithm is proposed to solve geophysical problems. It combines the advantages of deterministic inversion and neural network inversion in a coupled inversion scheme. The algorithm overcomes the limitations of neural networks in geophysical inversion by using a reference model to link the two inversion schemes. The results show that the adaptive physics-based neural network inversion is superior as it does not require preparing a training dataset but can still recover reliable resistivity models.
GEOPHYSICAL PROSPECTING
(2022)
Article
Geosciences, Multidisciplinary
Sudha Agrahari, Buelent Tezkan, Bernhard Siemon
Summary: Researchers extensively studied a Pleistocene buried valley, the Cuxhaven Valley, in Northern Germany using three different electromagnetic methods to analyze the underground structures, providing a basis for understanding the geological formations at various depths.
JOURNAL OF APPLIED GEOPHYSICS
(2021)
Article
Geochemistry & Geophysics
James Macnae, Xiuyan Ren, Tim Munday
Article
Geosciences, Multidisciplinary
Andrea Viezzoli, Giovanni Manca, Chris Wjins
JOURNAL OF APPLIED GEOPHYSICS
(2020)
Article
Environmental Sciences
J. Boaga, A. Viezzoli, G. Cassiani, G. P. Deidda, L. Tosi, S. Silvestri
SCIENCE OF THE TOTAL ENVIRONMENT
(2020)
Article
Geochemistry & Geophysics
James Macnae, Tim Munday, Camilla Soerensen
Article
Environmental Sciences
Peng Bai, Giulio Vignoli, Andrea Viezzoli, Jouni Nevalainen, Giuseppina Vacca
Article
Geochemistry & Geophysics
Andrea Viezzoli, Francesco Dauti, Chris Wijns
Summary: The industry has recognized that AEM data are often influenced by IP effects, but there is still a lack of understanding on the extent, location, and timing of IP presence. Researchers have developed a novel tool called the AIP scanner, which predicts the presence of AIP based on data space metrics and compares it with full AIP modelling results to identify areas affected by AIP. The AIP scanner map is a valuable tool for exploration industry to utilize AEM data information content.
EXPLORATION GEOPHYSICS
(2021)
Article
Geochemistry & Geophysics
Giulio Vignoli, Julien Guillemoteau, Jeniffer Barreto, Matteo Rossi
Summary: The analysis of surface wave dispersion curves is crucial for inferring the vertical distribution of shear wave velocity, with discussions on regularization strategies and the effectiveness of sparse reconstructions. The estimation of the depth of investigation using sensitivity kernels and the reliability of this estimation are also discussed in the presence of sharp boundaries.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Environmental Sciences
Jasmine Rutherford, Tania Ibrahimi, Tim Munday, Adrienne Markey, Andrea Viezzoli, Arianna Rapiti, Rod Paterson
Summary: This study focused on the hydrogeology of organic mound springs in the semi-arid Walyarta Conservation Park in northern Western Australia, using airborne geophysical data and remote sensing data to investigate the source and evolution of groundwater, and to understand the geological structures associated with the springs. The integrated datasets revealed the compartmentalized nature of sedimentary aquifers and landscapes in the park, providing insights into aquifer distribution, groundwater quality, and the presence of wetlands and phreatophytic vegetation.
Article
Geosciences, Multidisciplinary
Tim Klose, Julien Guillemoteau, Giulio Vignoli, Jens Tronicke
Summary: The study introduces a novel LCI approach for FDEM data using MGS regularization for vertical and lateral directions, providing a set of model solutions with different sharpness levels and variable lateral consistencies.
JOURNAL OF APPLIED GEOPHYSICS
(2022)
Article
Environmental Sciences
Luigi Tosi, Cristina Da Lio, Alessandro Bergamasco, Marta Cosma, Chiara Cavallina, Andrea Fasson, Andrea Viezzoli, Luca Zaggia, Sandra Donnici
Summary: This study proposes a new method for assessing the vulnerability of coastal farmland systems to saltwater intrusion. The sensitivity of the farmland system was evaluated by combining the depth of the freshwater/saltwater interface and the electrical resistivity of the shallow subsoil. The results show that about 30% of the farmland is under strong and extreme conditions, 28% is between marginal and moderate, and 40% is under negligible vulnerability.
Article
Geochemistry & Geophysics
Julien Guillemoteau, Giulio Vignoli, Jeniffer Barreto, Guillaume Sauvin
Summary: We have developed a 1D laterally constrained inversion technique based on the minimum gradient support regularization for surface-wave dispersion curves. The method allows for adjusting the sharpness of the solutions in the vertical and horizontal directions and has demonstrated good stability and convergence capabilities in other data tests.
Article
Engineering, Geological
Matteo Rossi, Roger Wisen, Giulio Vignoli, Mauro Coni
Summary: Distributed Acoustic Sensing (DAS) technology, which acquires acoustic vibrations via fiber optics sensors, has great potential for near-surface geotechnical applications. This study verifies the applicability of DAS in characterizing the shear-wave distribution, demonstrating its convenience as a non-invasive alternative to traditional methods.
ENGINEERING GEOLOGY
(2022)
Article
Geochemistry & Geophysics
Tim Klose, Julien Guillemoteau, Giulio Vignoli, Judith Walter, Andreas Herrmann, Jens Tronicke
Summary: Geophysical inverse problems often require regularization to provide a unique and stable solution. This study presents a structurally constrained approach for FD-EMI data inversion and demonstrates its effectiveness in reconstructing the subsurface electrical conductivity distribution, including its structural characteristics.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Environmental Sciences
Nicola Zaru, Matteo Rossi, Giuseppina Vacca, Giulio Vignoli
Summary: Frequency-domain electromagnetic induction (EMI) methods are commonly used for fast mapping, but they have limited frequencies and ill-posedness. Electrical resistivity tomography (ERT) methods are more reliable but time-consuming. This study demonstrates an improved EMI inversion method by incorporating additional prior information.
Article
Environmental Sciences
Peng Bai, Giulio Vignoli, Thomas Mejer Hansen
Summary: The study demonstrates that while using 1D forward modelling in airborne electromagnetic surveys is more computationally efficient than 3D inversions, it is important to consider the modeling error which can lead to false features in the reconstructions. Incorporating this information into the inversion process improves target reconstructions and ensures correct reliability estimates.