Print Email Facebook Twitter A commercial finite element approach to modelling Glacial Isostatic Adjustment on spherical self-gravitating compressible earth models Title A commercial finite element approach to modelling Glacial Isostatic Adjustment on spherical self-gravitating compressible earth models Author Huang, Pingping (Newcastle University; VolcanoTectonics Junior Research Group) Steffen, Rebekka (Geodata Division) Steffen, Holger (Geodata Division) Klemann, Volker (VolcanoTectonics Junior Research Group) Wu, Patrick (University of Calgary) van der Wal, W. (TU Delft Astrodynamics & Space Missions) Martinec, Zdeněk (Dublin Institute for Advanced Studies; Charles University) Tanaka, Yoshiyuki (University of Tokyo) Date 2023 Abstract This paper presents a method that modifies commercial engineering-oriented finite element packages for the modelling of Glacial Isostatic Adjustment (GIA) on a self-gravitating, compressible and spherical Earth with 3-D structures. The approach, called the iterative finite element body and surface force (FEMIBSF) approach, solves the equilibrium equation for deformation using the ABAQUS finite element package and calculates potential perturbation consistently with finite element theory, avoiding the use of spherical harmonics. The key to this approach lies in computing the mean external body forces for each finite element within the Earth and pressure on Earth's surface and core-mantle boundary (CMB). These quantities, which drive the deformation and stress perturbation of GIA but are not included in the equation of motion of commercial finite element packages, are implemented therein. The method also demonstrates how to calculate degree-1 deformation directly in the spatial domain and Earth-load system for GIA models. To validate the FEMIBSF method, loading Love numbers (LLNs) for homogeneous and layered earth models are calculated and compared with three independent GIA methodologies: the normal-mode method, the iterative body force method and the spectral-finite element method. Results show that the FEMIBSF method can accurately reproduce the unstable modes for the homogeneous compressible model and agree reasonably well with the Love number results from other methods. It is found that the accuracy of the FEMIBSF method increases with higher resolution, but a non-conformal mesh should be avoided due to creating the so-called hanging nodes. The role of a potential force at the CMB is also studied and found to only affect the long-wavelength surface potential perturbation and deformation in the viscous time regime. In conclusion, the FEMIBSF method is ready for use in realistic GIA studies, with modelled vertical and horizontal displacement rates in a disc load case showing agreement with other two GIA methods within the uncertainty level of GNSS measurements. Subject Creep and deformationLoading of the EarthMechanics, theory and modellingNumerical modellingStructure of the Earth To reference this document use: http://resolver.tudelft.nl/uuid:a5619e4b-0953-4ee3-beef-1ae6476c27f2 DOI https://doi.org/10.1093/gji/ggad354 ISSN 0956-540X Source Geophysical Journal International, 235 (3), 2231-2256 Part of collection Institutional Repository Document type journal article Rights © 2023 Pingping Huang, Rebekka Steffen, Holger Steffen, Volker Klemann, Patrick Wu, W. van der Wal, Zdeněk Martinec, Yoshiyuki Tanaka Files PDF ggad354.pdf 2.88 MB Close viewer /islandora/object/uuid:a5619e4b-0953-4ee3-beef-1ae6476c27f2/datastream/OBJ/view