Utilizing the towed Transient ElectroMagnetic method (tTEM) for achieving unprecedented near-surface detail in geological mapping

Sandersen, Peter B.E.; Kallesøe, Anders Juhl; Møller, Ingelise; Høyer, Anne‐Sophie; Jørgensen, Flemming; Pedersen, Jesper; Christiansen, A.V.

doi:10.1016/j.enggeo.2021.106125

Cited by 25 publications

(10 citation statements)

References 48 publications

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“…A new development in the field of time-domain EM is the tTEM-system, using a towed, ground-based, transient electromagnetic system, designed for detailed 3D geophysical and geological mapping of the shallow subsurface (0-80 m) in a fast and cost-efficient way (Auken et al 2019;Maurya et al 2020;Sandersen et al 2021). An all-terrain vehicle carries the instrumentation and tows the transmitter frame and the receiver coil which are mounted on sleds for a smooth ride over rough terrain.…”

Section: Resistivity Methodsmentioning

confidence: 99%

Geophysical methods help to assess potential groundwater extraction sites

Wiederhold

Kallesøe

Kirsch

et al. 2021

Grundwasser - Zeitschrift der Fachsektion Hydrogeologie

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Complex geology in glacial terrain makes groundwater exploration challenging for water supply companies. Abrupt lateral changes of geological conditions, for example, raise the risk of unsuccessful exploration drilling. At some locations, local water supply companies experience a large number of dry wells, raising the need for better exploration approaches. The use of geophysical techniques enables the detection and characterization of subsurface structures in terms of aquifers and aquitards.We present two examples in which seismic and resistivity methods are combined for subsurface characterization. A thrust structure is detected in the Varde study area in Denmark and a channel structure is mapped in the Hamburg-Sülldorf study area in Germany. The different imaging characteristics of seismic P‑ and S‑waves are demonstrated. The combination of seismic and resistivity methods enables delineating groundwater-bearing and groundwater-barrier layers down to a depth of 150 m.

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Section: Resistivity Methodsmentioning

confidence: 99%

Geophysical methods help to assess potential groundwater extraction sites

Wiederhold

Kallesøe

Kirsch

et al. 2021

Grundwasser - Zeitschrift der Fachsektion Hydrogeologie

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“…An important indicator for the performance of the induction magnetometers is sensitivity. The sensor output voltage corresponding to the unit magnetic induction intensity is defined as sensitivity, which can be expressed as equation (3). It can be seen from the above equation that the sensitivity of the magnetic core is related to the excitation frequency, the type and size of the magnetic core.…”

Section: Sensor Parameter Analysismentioning

confidence: 99%

“…There are many types of magnetotelluric methods, including time domain electromagnetic method (TEM), frequency domain electromagnetic method, and direct current method [3][4][5]. Among of these methods, frequency domain electromagnetic method is based on the theory of magnetotelluric method.…”

Section: Introductionmentioning

confidence: 99%

Parameter Optimization for the Induction Magnetometer of 10 kHz to 100 kHz

Li¹,

Huang

Ding³

et al. 2022

IEEE Access

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The induction magnetometers are widely applied for magnetotelluric detection due to the characteristics of wide frequency band, large detection depth range and small size. However, the key part of the induction magnetometersthe magnetic core has eddy current loss and hysteresis loss, which significantly affects the sensitivity of the induction magnetometers. In order to improve the sensitivity of the induction magnetometers at high frequencies, this paper investigates various parameters related to the performance of the induction magnetometers working at 10 kHz to 100 kHz. Moreover, optimization method is proposed to realize the development of a wide-band, high-sensitivity, and low-noise induction magnetometer. First of all, the parameters related to the sensitivity of the sensor are investigated according to the law of electromagnetic induction. A three-dimensional finite element (3D-FE) simulation model was established to study the influence of various parameters of induction magnetometers. In addition, an analysis method combining orthogonal experiment and response surface method is adopted to reduce the quantity of computations and improve the efficiency of analysis. The orthogonal experiment is able to obtain preliminary optimal parameters with only a small amount of computation results. Based on the results of the orthogonal experiment, the response surface method is used to illustrate the relationship between the sensor parameters and losses, and hence the optimal sensor parameters can be obtained. Finally, the model is verified by other sets of simulations, and the results show the regression coefficient of the model 2 0.9735 = R , indicating the effectiveness of the proposed model.

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“…1). The raw tTEM data were processed to suppress noisy data parts and then inverted to a resistivity model using spatially constrained inversion algorithm (Viezzoli et al, 2008). The resulting resistivity model consists of 57 862 1D models of 30 layers.…”

Section: Background and Summarymentioning

confidence: 99%

“…However, in such a stand-alone 1D inversion, each model is totally independent of the neighboring ones. To account for the lateral continuity expected in geological environments, the spatially constrained inversion (SCI) (Viezzoli et al, 2008) method was used. It applies 3D constraints to 1D inversion models both along and across the mapping lines, with a weight that is decreasing with distance.…”

Section: Inversionmentioning

confidence: 99%

tTEM20AAR: a benchmark geophysical data set for unconsolidated fluvioglacial sediments

Néven

Maurya

Christiansen

et al. 2021

Earth Syst. Sci. Data

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Abstract. Quaternary deposits are complex and heterogeneous. They contain some of the most abundant and extensively used aquifers. In order to improve the knowledge of the spatial heterogeneity of such deposits, we acquired a large (1500 ha) and dense (20 m spacing) time domain electromagnetic (TDEM) data set in the upper Aare Valley, Switzerland (available at https://doi.org/10.5281/zenodo.4269887; Neven et al., 2020). TDEM is a fast and reliable method to measure the magnetic field directly related to the resistivity of the underground. In this paper, we present the inverted resistivity models derived from this acquisition. The depth of investigation ranges between 40 and 120 m, with an average data residual contained in the standard deviation of the data. These data can be used for many different purposes: from sedimentological interpretation of quaternary environments in alpine environments, geological and hydrogeological modeling, to benchmarking geophysical inversion techniques.

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Utilizing the towed Transient ElectroMagnetic method (tTEM) for achieving unprecedented near-surface detail in geological mapping

Cited by 25 publications

References 48 publications

Geophysical methods help to assess potential groundwater extraction sites

Geophysical methods help to assess potential groundwater extraction sites

Parameter Optimization for the Induction Magnetometer of 10 kHz to 100 kHz

tTEM20AAR: a benchmark geophysical data set for unconsolidated fluvioglacial sediments

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