Why does it say "Achzari v'Evrah"?
Radak: Hashem will be cruel and angry with him.
Malbim: The day appears like a cruel one who tears without mercy, like a dark day wrapped in death, without order. If one is angry but does not have a cruel nature, or he is cruel, but now he is not angry, there is hope. This day He will be cruel at the time of His anger.
Why does it mention "Evrah" and "Charon Af"?
Malbim: Charon Af is only against the one who sinned against him. Evrah is getting angry to destroy also one who did not sin against him. On this day, His Evrah will destroy the entire country. His Charon Af will only be against the sinners.
Who are "Chata'eha"?
Rashi: Chot'eha (its sinners). Radak - the residents of Bavel, who are sinners. They will be eradicated from Bavel, until it remains desolate due to its residents' sins.
