Board Thread:Theories and Speculation/@comment-5407586-20150624095943/@comment-25079709-20150703155220

Earth sign is for controle clay. Like moving it and breaking it. For true explosion Deidara use Explosive Release via Katsu And yes, breaking C4 can be named explosion. 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. For example Naruto RasenShuriken also create explosion but with Wind chakra not with Explosive Release.