The numerical modelling of the first part of this work is extended to include a nonlinear elastic-plastic material response. The parameters for the rheological model are deduced from published soil tests and from the behavior of the field during the rebound phase which is assumed to be purely elastic. Unlike the linear case, the response of the plastic model is highly dependent on the stresses in the field prior to production. When these stresses are purely lithostatic and horizontally uniform the fit to observations is not significantly improved over the linear models. When a flexural prestress which accounts for the formation of the structural anticline of the field is included, simulations explain observations quite well.