Development of Grounded Electrical Source Airborne Transient EM (GREATEM)

Mogi, Tohru; Tanaka, Yoshikazu; Kusunoki, K.; Morikawa, Takeo; Jomori, Nobuhide

doi:10.1071/eg998061

Cited by 92 publications

(28 citation statements)

References 5 publications

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“…지상 송신원 항공 전자탐사에서는 강력한 1차장을 확보하기 위하여 양 끝이 접지된 긴 전선(long grounded-wire)을 송신원 으로 사용한다 (Mogi et al, 1998;Mogi et al, 2009 (Ward and Hohmann, 1987;Cho et al, 2015).…”

Section: Greatem 1차원 모델링unclassified

Laterally Constrained Inversion of GREATEM data

Cho¹,

Jang²,

Yi³

et al. 2017

Geophysics and Geophysical Exploration

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Recently, the grounded electrical-source airborne transient electromagnetic (GREATEM) system with high power source was introduced to achieve deeper investigation depth and to overcome high noise level. Although the GREATEM is a transient electromagnetic system using a long grounded wire as the transmitter, GREATEM data have been interpreted with 1D earth models because 2D or 3D modeling and inversion of vast airborne data are complicated and expensive to calculate. Generally, 1D inversion is subsequently applied to every survey point and combining 1D images together forms the stitched conductivity-depth image. However, the stitched models often result in abrupt variations in neighboring models. To overcome this problem, laterally constrained inversion (LCI) has been developed in inversion of ATEM data, which can yield layered sections with lateral smooth transitions. In this study, we analysed the GREATEM data through 1D numerical modeling for a curved grounded wire source. Furthermore, we developed a laterally constrained inversion scheme for continuous GREATEM data based on a layered earth model. All 1D data sets and models are inverted as one system, producing layered sections with lateral smooth transitions. Applying the developed LCI technique to the GREATEM data, it was confirmed that the laterally constrained inversion can provide laterally smooth model sections that reflect the layering of the survey area effectively.

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Section: Greatem 1차원 모델링unclassified

Laterally Constrained Inversion of GREATEM data

Cho¹,

Jang²,

Yi³

et al. 2017

Geophysics and Geophysical Exploration

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“…The method used in this study is the same as that described by Mogi et al (1998), Verma et al (2010Verma et al ( , 2013 Matsumoto and Kobayashi (1995) and Abd Allah el al. (2013a, b).…”

Section: Methodsmentioning

confidence: 99%

“…2) uses a 2-to 5-km-long grounded electrical dipole as a transmitting source and a three-component induction coil magnetometer that measures the time derivative magnetic field in a towed bird as a detector. Mogi et al (1998) illustrated theoretical transient responses of magnetic fields for horizontally layered structures and noted several features of the GREATEM response, such as the depth of investigation permitted by the large source-receiver distance. They highlighted the advantages of the system for investigating deeper structures and the possibility of identifying resistivity structure responses from sensor heights of 100 m or more, which is important for improving the safety of AEM surveys.…”

Section: Methodsmentioning

confidence: 99%

Three-dimensional resistivity modeling of GREATEM survey data from Ontake Volcano, northwest Japan

Allah

Mogi

2016

Earth Planet Sp

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Ontake Volcano is located in central Japan, 200 km northwest of Tokyo and erupted on September 27, 2014. To study the structure of Ontake Volcano and discuss the process of its phreatic eruption, which can help in future eruptions mitigation, airborne electromagnetic (AEM) surveys using the grounded electrical-source airborne transient electromagnetic (GREATEM) system were conducted over Ontake Volcano. Field measurements and data analysis were done by OYO Company under the Sabo project managed by the Ministry of Land, Infrastructure, Transport and Tourism. Processed data and 1D resistivity models were provided by this project. We performed numerical forward modeling to generate a three-dimensional (3D) resistivity structure model that fits the GREATEM data where a composite of 1D resistivity models was used as the starting model. A 3D electromagnetic forward-modeling scheme based on a staggered-grid finite-difference method was modified and used to calculate the response of the 3D resistivity model along each survey line. We verified the model by examining the fit of magnetic-transient responses between the field data and 3D forward-model computed data. The preferred 3D resistivity models show that a moderately resistive structure (30-200 Ω m) is characteristic of most of the volcano, and were able to delineate a hydrothermal zone within the volcanic edifice. This hydrothermal zone may be caused by a previous large sector collapse.

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“…The side length of the transmitter loop is usually several kilometers, and had make many testing surveys in Australia and Papua New Guinea over a number of mineral deposits [2] . Mogi et al from Japan developed a new airborne EM system named grounded electrical source airborne transient electromagnetic (GREATEM) system [3] . The GREATEM can obtain a greater depth of investigation using a grounded wire source and a long transmitter-receiver distance.…”

Section: Introductionmentioning

confidence: 99%

A New Semi-airborne Transient Electromagnetic System and Application of Detecting Underground Conductor in East Ujimqin Banner, China

Liu¹,

Huang²,

Liu³

et al. 2016

Proceedings of the 7th International Conference on Environment and Engineering Geophysics &Amp; Summit Forum of Chinese Academy

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Abstract-Airborne electromagnetic method (AEM) as an efficient, regional geophysical electromagnetic method has been widely used in geological survey, mineral exploration, environmental monitoring and other fields, but not in China for the civil aviation law and the safety consideration. We introduce a new semi-airborne transient electromagnetic (S-ATEM) system based on the unmanned aerial vehicle (UAV), and use a grounded electrical wire source which can provide a larger moment compare to the traditional AEM. We have taken an survey in East Ujimqin Banner, north east of China and the survey result indicates that the S-ATEM system has a greater investigation depth compared to the ground TEM system, and with more efficient, low cost, and safety.

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Development of Grounded Electrical Source Airborne Transient EM (GREATEM)

Cited by 92 publications

References 5 publications

Laterally Constrained Inversion of GREATEM data

Laterally Constrained Inversion of GREATEM data

Three-dimensional resistivity modeling of GREATEM survey data from Ontake Volcano, northwest Japan

A New Semi-airborne Transient Electromagnetic System and Application of Detecting Underground Conductor in East Ujimqin Banner, China

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