Linear stability analysis of the onset of sublithospheric convection

Landuyt, W, Ierley G.  2012.  Linear stability analysis of the onset of sublithospheric convection. Geophysical Journal International. 189:19-28.

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asthenosphere, couette-flow, Dynamics of lithosphere and mantle, Earth, generation and transport, heat, instabilities, Instability analysis, mantle, oceanic lithosphere, Small-scale convection, thermal-convection, variable viscosity


We consider the onset of small scale convection associated with the cooling of the oceanic lithosphere. This process is investigated by examining the linear stability of a 2-D shear flow that is cooled from the top and obeys an Arrhenius rheology. The perturbation equations are derived assuming a parallel flow, local 1-D analysis. The linear stability results are able to reproduce the structure and growth rate produced by solving the full non-linear equations. In addition, linear stability analysis predicts a similar dependence of onset times on activation energy and Rayleigh number as previous studies when small plate velocities are specified. Our linear stability analysis predicts a significant increase in the onset time with increasing plate velocity. Suggestions are given for the dynamical influence of plate velocity in reducing the convective forcing and delaying onset times.