3.8 KiB
FEMTIC
FEMTIC is a 3-D magnetotelluric inversion code based on the following studies. FEMTIC was made using object-oriented programming with C++.
Y. Usui, 3-D inversion of magnetotelluric data using unstructured tetrahedral elements: applicability to data affected by topography, Geophys. J. Int., 202 (2): 828-849, https://doi.org/10.1093/gji/ggv186, 2015.
Y. Usui, Y. Ogawa, K. Aizawa, W. Kanda, T. Hashimoto, T. Koyama, Y. Yamaya and T. Kagiyama, Three-dimensional resistivity structure of Asama Volcano revealed by data-space magnetotelluric inversion using unstructured tetrahedral elements, Geophys. J. Int., 208 (3): 1359-1372, https://doi.org/10.1093/gji/ggw459, 2017.
Y. Usui, T. Kasaya, Y. Ogawa and H. Iwamoto, Marine magnetotelluric inversion with an unstructured tetrahedral mesh, Geophys. J. Int., 214(2): 952-974, https://doi.org/10.1093/gji/ggy171, 2018.
The website of FEMTIC: https://sites.google.com/view/yoshiyausui/femtic
Functional overview
FEMTIC gives a three-dimensional electrical resistivity structure from the response functions at observation points on the Earth's surface.
Mesh type: tetrahedral mesh, hexahedral brick mesh, and non-conforming deformed hexahedral mesh
Data type: impedance tensor, vertical magnetic transfer function, inter-station horizontal magnetic transfer function, phase tensor, apparent resistivity, and phase.
Parallel computation: Hybrid MPI/OpenMP parallel calculation can be used.
Model parameter: Subsurface electrical resistivity and distortion matrix of galvanic distortion.
Release note
v4.1 Nov. 9, 2021: This new version supports difference filter. The error calculation of log10(apparent resistivity) is modified. Rotation angles of distortion matrix are limited to from -90 to 90 (deg.) when gains and rotations of galvanic distortion are estimated.
v4.0 Jun. 3, 2021: This new version supports non-conforming deformed hexahedral mesh.
v3.5 Jan. 11, 2021: This new version supports observed data of apparent resistivity and phase and unsymmetric roughening matrix.
v3.4.7 Sep. 4, 2020: The integer indices into the multiple right-hand-side vectors and solution vectors were changed from 32-bit to 64-bit.
v3.4.6 Sep. 2, 2020: This version allows us to make resistivity of every individual subsurface element to be a different model parameter, in analogy with other 3-D inversion code.
Pre/post-processing tools for FEMTIC
Some pre/post-processing tools for FEMTIC, including meshing tools, and their manuals can be downloaded from GitHub. Results of FEMTIC can be visualized by ParaView.
makeTetraMesh: By using this tool, you can make a surface mesh for creating a tetrahedral mesh.
makeMtr: This tool output .mtr file of TetGen by reading node and .ele files of TetGen.
TetGen2Femtic: This program converts output files of TetGen to FEMTIC.
makeDHexaMesh: Tool for making non-conforming deformed hexahedral mesh for FEMTIC
makeHexaMesh: Tool for making hexahedral brick mesh for FEMTIC
mergeResultOfFEMTIC: By this program, you can merge result files (.csv) of FEMTIC.
makeCutawayForGMT: By using this program, you can make a file needed to draw a cross-section of a resistivity structure by GMT.
changeResistivityForFemtic: By this program, you can change resistivity values of a specified area for sensitivity tests of FEMTIC inversion results