I would expect your game would generate the same animation of an explosion each time a player made one.
All other factors are what should be detectable. How I might do it:
Give points for good placement.
And points for what was used to make the explosion. (like engulfing more explosive fuel.)
Give points to more than one explosion animation touching. (if they touch, they could merge into a larger one.)
Give points to the amount of destruction done. (count the flying bits?)
If simultaneous explosions around the screen count as part of the one, add them up to see much screen they all took up.
Maybe it had factors that took points away too, how much they overlap structures that don't take damage, or
other hampering events, like rain, shields, or the repair-ability of what got blown up..
Your scenario might have other factors to give points for as well.