I am writing a paper talking about collisions during the formation of rocky planets. Some of these collisions lead to an increase in mass (i.e., the largest body to come out of a collision is more massive than either of the two bodies that were involved in the collision) and some collisions lead to a decrease in mass (i.e., the largest body to come out of a collision is less massive than either of the two bodies that were involved in the collision. I want a word to describe the second case, that the collision led to things getting smaller.
So far I have been using the word "erode" and its various forms, but "erode" means to make smaller over course of time, which doesn't match the situation I am trying to describe. Collisions are discrete (rather than continuous) events, and occur relatively quickly, such that the mass loss is nearly instantaneous. What would be a good word to describe this?