MATLAB and Python code for visualization and modeling of shear wave splitting observations:
- Optimized for the output of SplitLab (Wüstefeld et al. 2008) and StackSplit (Grund 2017).
- The modeling routine is applicable for the energy minimization method (Silver, Chan 1991).
- Extended and strongly modified from sws_tools by Michael Grund.
Example figures: Generated with the provided test data
- 001_stereoplot (MATLAB)
- 002_visualization (mainly Python, MATLAB)
- 003_modeling (MATLAB)
If you make use of this material, please acknowledge the relating publications in which framework these functions were implemented:
Peer-reviewed journal articles
- Fröhlich Y, Grund M, Ritter J R R (2024). Lateral and vertical variations of seismic anisotropy in the lithosphere-asthenosphere system underneath Central Europe from long-term splitting measurements. Geophysical Journal International, 239(1):112-135. https://doi.org/10.1093/gji/ggae245.
- Ritter J R R, Fröhlich Y, Sanz Alonso Y, Grund M (2022). Short-scale laterally varying SK(K)S shear wave splitting at BFO, Germany – implications for the determination of anisotropic structures. Journal of Seismology, 26:1137-1156. https://doi.org/10.1007/s10950-022-10112-w, correction https://doi.org/10.1007/s10950-023-10136-w.
Doctoral studies
- Fröhlich Y (2025a). Shear wave splitting analysis of long-term data: Anisotropy studies in the Upper Rhine Graben area, Central Europe. Dissertation, Karlsruhe Institute of Technology, Geophysical Institute. https://doi.org/10.5445/IR/1000183786.
- Fröhlich Y (2025b). Shear wave splitting analysis of long-term data: Anisotropy studies in the Upper Rhine Graben area, Central Europe. Disputation, Karlsruhe Institute of Technology, Geophysical Institute. https://doi.org/10.5281/zenodo.15982580.
- Fröhlich Y (2026a). Geophysical Visualizations. Zenodo. https://doi.org/10.5281/zenodo.15836682.
- Fröhlich Y (2026b). Geophysical Animations. Zenodo. https://doi.org/10.5281/zenodo.15641348.
Presentations
- Fröhlich Y (2026e). Resolving upper mantle anisotropy in 3-D from long-term data: A case study in the Upper Rhine Graben area, Central Europe. Workshop Integrating Seismic Anisotropy, Geodynamics, and Rock Deformation, St. Louis. https://doi.org/10.5281/zenodo.20441410.
- Fröhlich Y (2026d). Modeling shear wave splitting observations: Long-term data have the better idea. Annual Meeting of the German Geophysical Society, Münster, Germany. https://doi.org/10.5281/zenodo.18524089.
- Fröhlich Y, Ritter J R R (2024). Vertical and Small-scale Lateral Varying Seismic Anisotropy in the Upper Mantle Underneath the Upper Rhine Graben, Central Europe. Annual Meeting of the American Geophysical Union, Washington D.C.. Division Session Exploring Innovations and New Directions in Seismic Anisotropy and Attenuation: Observations, Models, and Experiments I Oral, DI21A-02. Abstract ID 1578275. https://doi.org/10.5281/zenodo.14510992.
Tested with: R2022a, R2021a,b under Linux and Windows
- MATLAB: Forward calculation
- Deep Learning Toolbox
- Mapping Toolbox
- MATLAB Seismic Anisotropy Toolkit (MSAT) (Walker, Wookey 2012)
- Data: Shear wave splitting observations
- Output *.txt files (nulls, splits) of SplitLab version 1.5.0 (Wüstefeld et al. 2008) or 1.2.1 (Porritt 2014)
- Output *.mat structure and *.txt files (STACK, SIMW) of StackSplit (Grund 2017)
- Colormaps (optional): Color-coding of the fast polarization direction and the root mean square error
- MatPlotLib Perceptually Uniform Colormaps
version v2.1.3, MATLAB File Exchange, last access 2022 June 26 - crameri perceptually uniform scientific colormaps
version v1.09, MATLAB File Exchange, last access 2023 April 10; based on Crameri (2021) - cmocean perceptually-uniform colormaps
version v2.02, MATLAB File Exchange, last access 2022 June 18; based on Thyng et al. (2016)
- MatPlotLib Perceptually Uniform Colormaps
| Release | Zenodo DOI | Publication | RADAR4KIT dataset |
|---|---|---|---|
| dev main branch |
|||
| v2.0 |  |
Fröhlich (2025a), Fröhlich et al. (2024) |
https://dx.doi.org/10.35097/685 |
| v1.0 |  |
Ritter et al. (2022) | https://dx.doi.org/10.35097/684 |
For details of the individual releases as well as for changes and differences compared to sws_tools by Michael Grund see the changelog.
- Modeling of multi-event analysis: Only using either STACK or SIMW results is supported
- Model parameter distribution for T1: Under development, not fully tested
- Synthetic stereoplot for T1 and H2: Backazimuths of predicted nulls are partly wrong
- Synthetic stereoplot for T1: Gray arrow is partly not exactly placed in the center
For bug reports, suggestions or recommendations feel free to open an issue or submit a pull request directly here on GitHub.
| Software | Language | Description | Author |
|---|---|---|---|
| MSAT | MATLAB | Toolkit for the analysis of elastic and seismic anisotropy | A M Walker, J Wookey |
| PyDRex | Python | Simulate crystallographic preferred orientation evolution in polycrystals | L Bilton, T Duvernay |
| PyRaysum | Python | Software for modeling ray-theoretical body-wave propagation | W Bloch, P Audet |
Shear wave splitting
- Bowman J R, Ando M (1987). Shear-wave splitting in the upper-mantle wedge above the Tonga subduction zone. Geophysical Journal International, 88(1):25-41. https://doi.org/10.1111/j.1365-246X.1987.tb01367.x.
- Grund M (2017). StackSplit - a plugin for multi-event shear wave splitting analyses in SplitLab. Computers & Geosciences, 105:43-50. https://doi.org/10.1016/j.cageo.2017.04.015.
- Porritt R W (2014). SplitLab version 1.2.1. available at https://robporritt.wordpress.com/software.
- Restivo A, Helffrich G (1999). Teleseismic shear wave splitting measurements in noisy environments. Geophysical Journal International, 137:821-830. https://doi.org/10.1046/j.1365-246x.1999.00845.x.
- Roy C, Winter A, Ritter J R R, Schweitzer J (2017). On the improvement of SKS splitting measurements by the Simultaneous Inversion of Multiple Waveforms (SIMW). Geophysical Journal International, 208:1508-1523. https://doi.org/10.1093/gji/ggw470.
- Silver P G, Chan W W (1991). Shear wave splitting and subcontinental mantle deformation. Journal of Geophysical Research, 96(B10):16429-16454. https://doi.org/10.1029/91JB00899.
- Walker A M, Wookey J (2012). MSAT — A new toolkit for the analysis of elastic and seismic anisotropy. Computer & Geosciences, 49:81-90. https://doi.org/10.1016/j.cageo.2012.05.031. available at https://www1.gly.bris.ac.uk/MSAT/, https://github.com/andreww/MSAT.
- Wolfe C J, Silver P G (1998). Seismic anisotropy of oceanic upper mantle: Shear wave splitting methodologies and observations. Journal of Geophysical Research: Solid Earth, 103(B1):749-771. https://doi.org/10.1029/97JB02023.
- Wüstefeld A, Bokelmann G, Zaroli C, Barruol G (2008). SplitLab: A shear-wave splitting environment in Matlab. Computers & Geosciences, 34(5):515-528. https://doi.org/10.1016/j.cageo.2007.08.002.
PyGMT and GMT
- Tian D, Fröhlich Y, Leong W J, Grund M, Schlitzer W, Jones M, Uieda L, Luis J M F (2026). PyGMT: Bridging Python and the Generic Mapping Tools for Geospatial Visualization and Analysis. Geochemistry, Geophysics, Geosystems, 27(7), e2026GC013105. https://doi.org/10.1029/2026GC013105.
- Tian D, Leong W J, Fröhlich Y, Grund M, Schlitzer W, Jones M, Toney L, Yao J, Tong J-H, Mage Y, Materna K, Belem A, Newton T, Anant A, Ziebarth M, Quinn J, He X, Uieda L, Wessel P (2024). PyGMT: A Python interface for the Generic Mapping Tools, version v0.19.0. Zenodo. https://doi.org/10.5281/zenodo.19398871 (v0.19.0), https://doi.org/10.5281/zenodo.3781524 (all versions / latest version).
- Wessel P, Luis J F, Uieda L, Scharroo R, Wobbe F, Smith W H F, Tian D (2019). The Generic Mapping Tools version 6. Geochemistry, Geophysics, Geosystems, 20(11):5556-5564. https://doi.org/10.1029/2019GC008515.
- Wessel P, Luis J F, Uieda L, Scharroo R, Wobbe F, Smith W H F, Tian D, Jones M, Esteban F, Fröhlich Y (2025). The Generic Mapping Tools, version 6.6.0. Zenodo. https://doi.org/10.5281/zenodo.16448627 (6.6.0), https://doi.org/10.5281/zenodo.3407865 (all versions / latest version).
Colormaps
- Crameri F (2021). Scientific colour maps, version 7.0.1. Zenodo. https://www.fabiocrameri.ch/colourmaps.php. https://zenodo.org/record/5501399.
- Thyng K M, Greene C A, Hetland R D, Zimmerle H M, DiMarco S F (2016). True colors of oceanography: Guidelines for effective and accurate colormap selection. Oceanography, 29(3)9-13. https://dx.doi.org/10.5670/oceanog.2016.66.
The presented research and YF received support from various sources:
- Graduate Funding from the German States (scholarship)
- NSF EAR-1948602 (travel support to AGU24)
- DFG project 521545943 (research assistant within DFG Priority Program DeepDyn SPP 2404 – 500707704)
- NSF EAR-2153910 (travel support to workshop Integrating Seismic Anisotropy, Geodynamics, and Rock Deformation)