Board Thread:Theories and Speculation/@comment-5407586-20150624095943/@comment-25079709-20150703162956

Ok. It exploded. But because it's unlike every other explosion done with Explosive Release (even Gari) I think Deidara did this with Earth Release via Earth sign. In Naruto world explosion can be achived in many different ways: with Katon, Suiton, Fuuton, ect. But explosion with Explosive Release is different and Deidara always do Katsu before it

EDIT: I FOUND IT! :D Here you even have explosion via Doton