Resolution analyses for the tellus airborne electromagnetic data compared with co-located electrical resistivity tomography data
Bayat, Somaye
Bayat, Somaye
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Publication Date
2023-09-11
Type
Thesis
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Abstract
This thesis investigates and compares the capabilities of frequency- and time-domain air borne electromagnetic (AEM) data acquired as part of the geophysics surveys of the Tellus programme, which is operated by the Geological Survey Ireland. aempy(x) toolbox writ ten and developed by the Dublin Institute for Advanced Studies researchers is used for forward and inverse modelling of both synthetic and observed Tellus data. As part of the investigation, synthetic data are simulated using two simple three-layer Earth models. The shallow model comprises 15 m thick first layer with a resistivity of 100 Ωm, 25 m thick middle layer with a resistivity of 5 Ωm, and a lower half-space with a resistivity of 100 Ωm, respectively. The deep model comprises 50 m thick first layer with a resistivity of 100 Ωm, 50 m thick middle layer with a resistivity of 10 Ωm, and a lower half-space with a resistivity of 100 Ωm. The inversion process has considered parameters includ ing flight altitude, data errors, and input data, which can have significant effects on the resulting electrical conductivity models. The simulation results show that the simulated frequency-domain data at the flight altitudes of 60 – 120 m have done a much better job recovering the conductive middle layer of the shallow model. On the other hand, time domain data successfully recovered the first two layers of the deep model even at the high flight altitudes, i.e., 100, 120, and 150 m. The electrical resistivity models derived from the Tellus AEM datasets were compared against the Electrical Resistivity Tomography (ERT) derived resistivity models. The inversion results show that there is a good corre spondence between the ERT model and the Tellus TDEM model at greater depths. The Tellus FDEM data successfully resolved the conductivity of the top layer, which is in good agreement with the ERT model.
Funder
Geological Survey of Ireland
Sustainable Energy Authority of Ireland
Sustainable Energy Authority of Ireland
Publisher
NUI Galway