Adam Clarke on Micah 1:3

For, behold, the Lord cometh forth - See this clause, Amo 4:13 (note). He represents Jehovah as a mighty conqueror, issuing from his pavilion, stepping from mountain to mountain, which rush down and fill the valleys before him; a consuming fire accompanying him, that melts and confounds every hill and dale, and blends all in universal confusion. God is here represented as doing that himself which other conquerors do by the multitude of their hosts; levelling the mountains, filling some of the valleys, and digging for waters in others, and pouring them from hills and dales for the use of the conquering armies, by pipes and aqueducts.

And why is all this mighty movement? Mic 1:5. "For the transgression of Jacob is all this, and for the sins of the house of Israel."