A parasitic cone (or satellite cone) is the cone-shaped accumulation of volcanic material not part of the central vent of a volcano. One forms by eruptions from fractures on the flank of the volcano. These fractures occur because the flank of the volcano is unstable. Eventually the fractures reach the magma chamber and generate eruptions called flank eruptions which in turn produce a parasitic cone.
A parasitic cone can also be formed from a dike or sill cutting up to the surface from the central magma chamber in an area different from the central vent.