  According to previous work on magnetic monopoles, static regular solutions
are nonexistent if the vacuum expectation value of the Higgs field $\eta$ is
larger than a critical value $\eta_{{\rm cr}}$, which is of the order of the
Planck mass. In order to understand the properties of monopoles for
$\eta>\eta_{{\rm cr}}$, we investigate their dynamics numerically. If $\eta$ is
large enough ($\gg\eta_{{\rm cr}}$), a monopole expands exponentially and a
wormhole structure appears around it, regardless of coupling constants and
initial configuration. If $\eta$ is around $\eta_{{\rm cr}}$, there are three
types of solutions, depending on coupling constants and initial configuration:
a monopole either expands as stated above, collapses into a black hole, or
comes to take a stable configuration.
