Numerical Modeling of Extensional Necking Instabilities: Application to Ganymede's Grooved Terrain

Ganymede s pervasive 5-10 km-wavelength grooves have been suggested to result from a necking instability during an epoch of lithospheric extension, but to date few quantitative studies of groove formation have been performed. We present two-dimensional numerical models of necking instabilities under conditions that are appropriate to Ganymede at the time of groove formation. Preliminary simulations indicate that extensional necking instabilities can occur under a range of conditions, many of which may be relevant to Ganymede. The form of the surface topography produced by these instabilities varies as a function of the strain rate, amount of extension, initial topographic perturbation, and rheological parameters.