  Vulcanian explosive eruption, which is a nonlinear and nonequilibrium abrupt
dynamics of magma-gas mixture, is modeled by a two-component Lennard-Jones
particle system. Molecular-dynamics simulation of a shock-tube experiment gives
consistent results with a explosive eruption picture of volcanology; Shock wave
and expansion wave are reproduced. In addition bubble nucleation of a gas
component in the magma melt and spinodal-like decomposition are observed in the
simulation. The result is also compared with a continuum hydrodynamic model;
Qualitative features of continuum dynamics are reproduced by the present model.
We find that the particle description of dynamics is an effective method in
such kind of abrupt dynamics.
