Setting up initial conditions for geodynamic systems in computational modeling codes vary in difficulty. Models which are geometrically very simple are easy to make with the help of a few if and else statements in a code or perhaps through a function parser. Similarly, very realistic present day instantaneous models using data from, for example, seismic tomography can also be straight forward to construct once a relationship between the seismic anomaly and temperature has been developed. However, a problem arises when constructing a realistic evolutionary model starting in the geologic past. Using a function parser approach for this kind of problem results in extremely long and complicated sets of equation which are not easy to construct and very hard to modify. The Geodynamic World Builder (GWB) is designed to address these problems by allowing users to construct complex models that are easily modified and shared, thereby promoting reproducibility and open science.
GWB is an open source code library intended to help users set up initial conditions in computational geodynamic models in both Cartesian and spherical geometries. Instead of using a function parser approach, the GWB abstracts geodynamic/tectonic features allowing users to define their shapes and properties, and place them into the model world. This is done through an easy to read and write JSON-style input file (see figure). Examples of such features are a continental plate, an oceanic plate, a subducting plate, and a fault. Based on the chosen parameterization, users can visualize the result directly as a vtu (paraview) file or pass the GWB input file to a geodynamic code coupled to the GWB. This geodynamic code will then use this file to set up and query the GWB to retrieve the initial conditions for temperature and composition.
The GWB is written in C++, but can be used by geodynamic codes in nearly all programming languages through its C and Fortan wrappers. GWB has been successfully coupled to and used with ASPECT (C++ FEM), EleFant (Fortran FEM), and SEPRAN (Fortran FEM). The GWB is presented in doi.org/10.5194/se2019-24 and comes with an extensive manual which can be found at geodynamicworldbuilder.github.io.
Contributed by Menno Fraters
Fraters, M., Thieulot, C., van den Berg, A., and Spakman, W.: The Geodynamic World Builder: a solution for complex initial conditions in numerical modelling, Solid Earth Discuss., https://doi.org/10.5194/se-2019-24, accepted 2019.
Figure. Example JOSN file for building a simple model in GWB.