Geophysical globe: Dynamic topography

Dynamic topography is caused by density variation and flow in the convecting mantle, perturbing the Earth's surface by +/- 1 km with wavelengths generally over 800 km. Here, we visualise the Hoggard 2016 model (https://www.nature.com/articles/ngeo2709) by perturbing the surface of a globe with recognisable continents and surface topographic features.

Glue together with superglue to create the final globe.

Context

Measurements and models of global geophysical parameters such as potential fields, seismic velocity models and dynamic topography are well represented as traditional contoured and / or coloured maps. However, as teaching aids and for public engagement, they offer little impact. Modern 3D printing techniques help to visualise these and other concepts that are difficult to grasp, such as the intangible structures in the deep Earth.

For methodologies and discussion of the value of these physical objects, see our article https://www.frontiersin.org/articles/10.3389/feart.2021.669095/abstract

How I Designed This

see https://github.com/jeffwinterbourne/3D_globes/

To create the model, we apply a bump mapto the surface of as sphere, using UV mapping in the open source Blender software. The bump map consists of a equirectangular projected greyscale image, unadorned, where white corresponds to the highest desired topographic point and black the lowest. Models can then be exported in the widely used STL format.

Models are sliced into northern and southern hemispheres and hollowed before printing - this minimises the amount of plastic and time required for printing. This can also be accomplished in Blender prior to export, or in PrusaSlicer