Earth curvature effects on subduction morphology: Modeling Subduction in a spherical setting with the Fast Multipole Boundary Element Method


Morra G., Chatelain P., Tackley P., Koumoutsakos P., Acta Geotechnica, in Press, 2008



We present here the first application in Geodynamics of a (Fast ultipole) Accelerated Boundary Element Method (Accelerated-BEM) for tokes flow. The approach offers the advantages of a reduced number of computational elements and linear scaling with the problem size. We show that this numerical method can be fruitfully applied to the simulation of several geodynamic systems at the planetary scale in spherical coordinates and we suggest a general approach for modeling combined mantle convection and plate tectonics. The first part of the paper is devoted to the technical exposition of the new approach, while the second part focuses on the effect layed by Earth curvature on the subduction of a very wide oceanic ithosphere (W = 6000km and W = 9000km), comparing the effects of two different planetary radiuses (ER = 6371km, 2ER = 2 · 6371km), corresponding on ”Earth like” model (ER) and to a ”flat Earth” one (2ER). The results show a distinct difference between the two models: while the slab on a ”flat Earth” shows a slight undulation, the same subducting plate on the ”Earth like” setting presents a dual behavior characterized by concave curvature at the edges and by a folding with wavelength of the order of magnitude of 1000km at the center of the slab.