“I have (yet another) dumb question: if the muslims are bunkered in tunnels, what good does a large blast on the surface do?”
Two things:
1. The concussion of the explosion collapses the mouths of some of the tunnels
2. (This is the biggie) it pulls all the air out of the tunnels so that whoever is hiding there suffocates.
Actually it can also turn their lungs inside out...
Don’t forget the fire.