Board Thread:Theories and Speculation/@comment-1512913-20161115123051/@comment-734582-20161116100600

-Arias- wrote: Except it makes sense for Explosion to be Earth, since Sasuke's electric attacks nullified Deidara's explosives. It was more than just Sasuke's word. The way Deidara uses clay for bombs (unlike other Blast users who could focus it from anywhere) suggests that the Earth Release is necessary for the jutsu. It doesn't mean that Earth Release is part of Blast Release.

So basically Deidara uses some secret Earth Ninjutsu that allows the creation of bombs, which are filled with Blast Release chakra. Lighting attacks the Earth part of the jutsu, not the Blast Release (so whatever trigger is present is defused). Else, i'd expect the bombs to explode when the lighting triggers the bombs.