Budi Laksono, Agung and Anggraini Putri, Witta and Iskandar, Chevy and Sapto Mulyanto, Bagus (2018) Magnetotelluric Phase Tensor Application to Geothemal Modeling. Jurnal Geofisika Eksplorasi. ISSN 2356-1599

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Abstract

Phase tensor analysis generate invariant parameters of phase tensor ellipticity and phase tensor skew angle determines the dimensionality of regional impedance tensor and geoelectrical strike. Geoelectrical strike and dimensionality information generated by the phase tensor of the regional structure can used to remove the galvanic distortion from measured impedance tensor and number of assumed parameters required to remove galvanic distortion is a function of this dimension. As key equation for galvanic distortion is Z = DZR so regional impedance tensor can be rewritten as ZR = D- 1Z. And D-1 is derived after the dimension information provided by phase tensor and accordingly one, two and four assumptions are made for 1D, 2D and 3D structures for the removal of galvanic distortion. The invariant parameters of the phase tensor, such as the ellipticity (Φmax and Φmin) and slope angle of phase tensor (β) determine the dimensionality of the impedance tensor. If the structure of 1-D, then Φmax and Φmin will be equal, so the phase tensor form will be a circle with β is zero or near zero, for structur of 2-D the value Φmax ≠ Φmin while β is still zero or near zero and for 3D structure all components in tensor each impedance has a value and β ≠ 0 with a value of β> 3 °. The results of the above phase tensor analysis show that the 1-D and 2-D structures are shown at frequencies of 320 Hz to 0.2 Hz (the period of 0.0031s to 5.4s) and 3-D structures are shown at less from frequencies 0.11 Hz (period 9.588s). If the graphical representation non-symmetrical ellipse 2-D to the ellipse axis this because β ≠ 0, so it needs to be rotated to the ellipse axis with the angular value generated by calculation of α-β is -10o. The angle α − β defines direction of the major axis of the tensor ellipse in the Cartesian coordinate system used to express the tensor. Knowing the orientation of the major axis the ellipse may then be constructed from knowledge of the lengths of the major and minor axes (i.e. from max and min). A more direct and simpler way of drawing the tensor ellipse is to recall that the matrix representing the tensor can be thought of as mapping of one vector into another. This is easily and compactly implemented in modern computer languages such as MATLAB.

Item Type: Article
Subjects: Q Science > QE Geology
Divisions: Fakultas Teknik (FT) > Prodi Teknik Geofisika
Depositing User: BAGUS SAPT
Date Deposited: 28 Jun 2018 06:50
Last Modified: 28 Jun 2018 06:50
URI: http://repository.lppm.unila.ac.id/id/eprint/8100

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