Details of the abstract

Title of paper Three-Dimensional Inversion of Magnetotelluric Data from the Tarawera Dome Complex, New Zealand
List of authors Semper, P., Bertrand, E. A., Caldwell, G., Heise, W., Scheunert, M., Spitzer, K.
Affiliation(s) TU Bergakademie Freiberg, GNS Science, GNS Science, GNS Science, TU Bergakademie Freiberg, TU Bergakademie Freiberg
Summary We have merged our long-term numerical software developments at TU Bergakademie Freiberg and TU Chemnitz into a finite element toolbox that now provides blueprints for the implementation of forward operators and inversion routines for arbitrary geophysical EM problems.
Here we present an application of this toolbox to the magnetotelluric method by inverting both synthetic and real MT field data sets to study the behaviour of the implemented numerical solutions and prove the applicability to large field data sets. The MT data were acquired by GNS Science at 68 sites over an area of 25 x 30 km2 at the Tarawera Dome Complex, New Zealand, from 2006 to 2017. For the 3D inversion, we have used 16 periods between 0.013 s and 341.297 s and placed particular emphasis on an appropriate representation of the rugged topography.
For the synthetic case, we have used the targeted field dataset as a guide. A simplified model of the Tarawera Dome Complex has thus been created to generate a synthetic data set. The model is based on the knowledge of the regional geology and an analysis of the raw data. It consists of four main layers and two conductive plume-like structures.
For the inversion of the synthetic data, we have restricted ourselves to the impedances which leads to the resolution of the stratigraphy in terms of layer thicknesses and resistivities. However, the plume-like structures were not resolved.
The 3D inversion of the impedances of the real data set yields very similar results to the ones obtained in previous studies. Two conductive plume-like structures, which seem to rise from a larger conductive zone at depth, are well resolved.
Both studies give us positive feedback regarding the practical inversion of extensive MT field datasets with our toolbox.
Session Keyword 2.0 Theory, Modelling and Inversion
File upload 2.0_three-dimensional_inversi_semper_02.pdf
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