Research highlight

Robust and efficient visualization tools are essential for Earth scientists to effectively uncover patterns and trends in data and models to interpret Earth's interior and processes. Meanwhile, emerging visualization techniques also play a crucial role in public outreach to create engaging and effective ways to share scientific results with the public and inspire students to STEM fields by transforming abstract data into visually compelling 3D experiences. 

Virtual Reality (VR) and planetarium theaters provide unprecedented opportunities for the scientific community to interact with their audiences. As part of the NSF-funded SPAC-MAN (Slabs, Plumes, And Convection in MANtle) project, we facilitate 3D visualization for exploring data and models to advance education and public outreach promoting deep-Earth geophysical studies. To demonstrate the use of immersive environments in different branches and scales, we build an interactive user experience using the global adjoint tomographic mantle models as the basis, which are constructed based on 3D numerical modeling of synthetic seismograms and data sensitivity kernels capturing the full complexity of global wave propagation using the global wave propagation solver SPECFEM3D_GLOBE (Komatitsch & Tromp 2002) hosted by CIG.

During our first demonstrations in VR and planetariums, we used the transversely isotropic GLAD-M25 (Lei et al. 2020) as the background mantle model to highlight the main slab and plume features. GLAD-M25 is a transversely isotropic global mantle model based on data from 1480 earthquakes assimilated within a global full-waveform inversion framework to invert crust and mantle simultaneously down to the core-mantle boundary. We started demonstrating the effective exploration of Earth's mantle to enhance the learning process of undergraduate and graduate students and promote global geophysics and deep-Earth studies initially at the Colorado School of Mines and in the broader Denver area through public outreach activities in collaboration with the Denver Museum of Nature & Science (DMNS).

For visualization in VR and planetariums, we follow a three-step pipeline. We first use Paraview to create 3D cross-sections and contour plots (i.e., slabs, plumes, etc.) from the background tomographic models. The model files are then exported to Blender, which serves as an intermediary step to make corrections and adjust the models for Unity, which is used to display models in VR headsets, and OpenSpace to display on planetariums. 

Immersive VR environments offer a more interactive experience, allowing the public to control their own learning path. The first VR demonstration of the global mantle models was with the Applied Mathematics & Statistics and Geophysics students at the Colorado School of Mines on November 7, 2023, as part of the Math Club activities of the Applied Mathematics & Statistics Department, focusing on deep mantle plumes. After a brief introduction to mantle plumes and how they are imaged with seismic waves generated by earthquakes and seismic tomography, the students explored mantle plumes using VR headsets, which led to discussions on their origin and importance, super plumes, and other deep mantle plumes all around the globe, their connection to the surface processes and the challenges in seismic tomography to image them and determine their resolution. In Figure 1, some snapshots from students' experiences are shown. 

As an example of a broader public outreach activity, on December 4, 2023, we gave a public lecture, Journey to the Center of the Digital Earth with Earthquakes, on mantle plumes and their connection to surface processes like earthquakes and volcanic activity to a sold-out audience at the DMNS Gates Planetarium (Figure 2). This 120-seat theater has eight projectors that seamlessly tile the hemispherical display with computer servers that can playback pre-rendered science documentary films or present immersive environments generated by interactive real-time visualization software (Neafus & Yu 2007). This allows large assembled groups to have a shared immersive experience, as opposed to the single user in a VR headset. Digital globe features in OpenSpace, the planetarium software, allow for multi-resolution visualizations of spatialized geophysical, biophysical, and sociological data. A shorter version of the lecture was also given to the American Geophysical Union's attendees at the Morrison Planetarium in San Francisco on December 13, 2023 (Figure 3). We will continue our lectures, also including subducted slabs to give an overall view of the deep Earth and planetary processes and how they shape the surface of the Earth and other planets. 

Looking ahead, the project aims to expand beyond mantle plumes, incorporating features such as slabs, seismicity, anisotropy, and other geophysical data in upcoming VR and planetarium demonstrations. 

The SPECFEM code is currently available through Computational Infrastructure for Geodynamics. Visit their website at specfem.org.

Contributed by: Austin Hoyle, Ridvan Örsvuran, Ka Chun Yu, and Ebru Bozdağ, Colorado School of Mines, Denver Museum of Nature & Science

Acknowledgements
The project is supported by the National Science Foundation under Award No. EAR1945565.

Paraview, Blender, Unity and OpenSpace are free to download. OpenSpace is open source software.

References
Komatitsch, D., & Tromp, J. (2002). Spectral-element simulations of global seismic wave propagation-I. Validation. Oxford University Press (OUP). https://doi.org/10.1046/j.1365-246x.2002.01653.x

Lei, W., Ruan, Y., Bozdağ, E., Peter, D., Lefebvre, M., Komatitsch, D., … Pugmire, D. (2020). Global adjoint tomography—model GLAD-M25. Oxford University Press (OUP). https://doi.org/10.1093/gji/ggaa253

Neafus, D., & Yu, K.C. (2007). Performing and Visual Arts, The Sciences: Visualization brings them together at the Gates Planetarium. The Planetarian, 36(3), 6–17.