Why does it say "[Al Ken] Shamayim Argiz"?
Rashi (from Tanchuma Beshalach 13): All the Heavenly legions will be agitated when I make the Sar of (angel appointed over) Bavel fall. Hashem takes payment from the nations only after He takes payment from their Sarim - "Yifkod Hashem Al Tzeva ha'Marom ba'Marom" (14:21), and afterwards on kings of the land; "Eich Nafalta mi'Shamayim Heilel ben Shachar", and afterwards "Nigdata la'Aretz Cholesh Al Goyim" (14:12). Also here, first I will agitate Shamayim, and afterwards the land will tremble, due to the report of its fall; people will be astounded.
Radak: It is a metaphor, as if Shamayim will be agitated and the land will tremble due to the great evil that comes on Bavel. No sum of money can save them from the sword (12).
Malbim: When I punish Bavel for those whom they killed (12), I will uproot also their source and Mazal above. Via agitating Shamayim, which surrounds the land, automatically the land will tremble
Why does it mention "Evrah" and "Charon Af"?
Malbim: Refer to 13:9:2:1.
