Board Thread:Theories and Speculation/@comment-26379028-20150523070516/@comment-26023629-20150524174912

Well... It's not canon, and all the earth combinations are, theoretically, already taken. So, nothing, really.

I suppose if you don't buy the logic on magnet or explosion release, it could be one of those combinations.

Unlike a lot of others, explosion being lightning+earth sorta makes sense to me. They're the most opposite of all the elements: solid matter, and pure energetic plasma. The two chakras simply don't want to mix and reject each other, blowing up. It also reflects why earth is weak to lightning: it breaks it up, or shatters it.