Why are asteroids explosive?

Large meteoroids/small asteroids have very high velocities, accelerations, and potential energy when they burn up in an atmosphere and impact a larger celestial body. All that energy very quickly pulverizes dirt and rocks and may even melt the rocks, if is big and mive enough, in the area where the meteorite impacts the surface. By themselves asteroids and meteoroids are not explosive. It's the velocity, acceleration, potential and kinetic energies of the asteroid /meteoroid that make it explosive. The surface of ANY meteorite right after impact is NOT "ice cold." You should wait until the surface cools down before touching it.