See Revelation 4:5, Revelation 6:12 11:13,19. Either declarative of the majesty and power of God, \as Exodus 19:16, when God came forth to give his law\ the violation of which God here was coming out to punish; or of the great stirs and confusions in that part of the world where the beast's greatest interest lay. Or, the voices, thunders, and lightnings, may be understood as declarative of the former, and the great earthquake of the latter.
Related Commentaries of Revelation 16:18
Revelation 16:18
18 And there were voices, and thunders, and lightnings; and there was a great earthquake, such as was not since men were upon the earth, so mighty an earthquake, and so great.