The Blast element says it may have the secondary effect to "shatter, knock over, shred, or otherwise sweep away" anything with less structure then it's Force.
I can't find the specific section, but I believe I remember it being stated that when force is needed for a magical effect on a critter, to use the creature's magic in place of force.
If this is so, does that make a case for an Adept with Elemental Strike [Blast], and magic 6 to break moderately durable items (like ballistic glass- structure 5) very easily, even if his actual damage is 1-2P (1-3 strength and the required Killing hands power), and few unarmed combat dice?
I'm sure this also applies to the knock down of Blast and Water effects, that in the case of an eleental strike or attack of these elements, the magic rating of the creature would be added to the damage, since an actual "force" for the effect is not present.