Explosive volcanic eruptions are certainly one of the most complex phenomena occurring in nature. In addition, the occurrence of pyroclastic flows, i.e. of high-velocity and high-temperature ground-hugging flows produced by the collapse of volcanic column, represent a very hazardous phenomenon for the nearby urbanized areas. To study and better understand this phenomena a parallel computer code able to simulate 3D pyroclastic flows (PDAC) has been developed. It turns out that supercomputers are required to run sufficiently accurate simulations with realistic flow conditions of explosive volcanic eruptions.