  In this paper we study the effects of a toroidal magnetic flux tube emerging
into a magnetized corona, with an emphasis on large-scale eruptions. The
orientation of the fields is such that the two flux systems are almost
antiparallel when they meet. We follow the dynamic evolution of the system by
solving the 3D MHD equations using a Lagrangian remap scheme. Multiple
eruptions are found to occur. The physics of the trigger mechanisms are
discussed and related to well-known eruption models.
