femticPy

femticpy is a Python module to create inputs / read outputs of FEMTIC, a 3-D magnetotelluric inversion code (Usui, 2015).

femticpy is a python module that allows to:

• create the input observed data file from a list of .edi files
• prepare the files required to generate a mesh
• read, plot and QC the result of the inversion

CSIRO Collection

http://hdl.handle.net/102.100.100/636092?index=1

Workflow

The workflow consists in:

1. Create topography, bathymetry and coast line files using the notebook prep_topo_bathy.ipynb
2. Create input files to create the mesh and inversion files using the notebook prep_inversion.ipynb
3. Create the mesh using the pipeline create_mesh.sh, that calls the Pre/post-processing tools (available on FEMTIC Repo)
4. Run the inversion using run_inversion.sh, that calls the femtic executable
5. Analyse and plot the inversion results using the notebook femtic_results.ipynb

The module can be used using the Jupyter notebooks provided in the examples directory. 3 examples are provided:

• A real data example in examples/auslamp, to create a mesh in a coastal area, run the inversion and QC inversion results (.edi files can be found on the Geological Survey of South Australia website: https://www.energymining.sa.gov.au/industry/geological-survey/gssa-projects/em-geophysics)
• a synthetic MMT data example in examples/mmt, to create a mesh in a full marine environment using real bathymetry data
• a synthetic land MT example examples/synthetic, toy example that can be run quickly to test the inversion of Z and VTF data

Notes

• Models can be visualized in Paraview
• The directory structure for each new project has to be copied from the empty_project directory
• The edi files read well when exported from winglink or geotools, other formats can cause problems
• The following codes must be compiled:
  • femtic (inversion executable)
  • makeMtr (Pre/post-processing tools)
  • makeTetraMesh (Pre/post-processing tools)
  • tetgen (https://github.com/libigl/tetgen)

Dependencies

• pyproj
• rdp
• shapely
• pandas > 1.5

References:

Papers:

1. 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).

2. 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.

3. 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.

FEMTIC repository:

https://github.com/yoshiya-usui/femtic

FEMTIC website:

https://sites.google.com/view/yoshiyausui/femtic

Resources / Manuals:

Manual_Of_FEMTIC_v4.1.pdf (https://github.com/yoshiya-usui/femtic/tree/main/doc)

How_To_Make_Tetra_Mesh_For_FEMTIC.pdf (https://github.com/yoshiya-usui/makeTetraMesh/tree/master/doc)

License

MIT