Jamieson, Fausset and Brown on Jeremiah 48:31

31. I will cry ... for ... Moab--Not that it deserves pity, but the prophet's "crying" for it vividly represents the greatness of the calamity.

Kir-heres--Kir-hareseth, in Is 16:7; see on Is 16:7. It means "the city of potters," or else "the city of the sun" [Grotius]. Here "the men of Kir-heres" are substituted for "the foundations of Kir-hareseth," in Is 16:7. The change answers probably to the different bearing of the disaster under Nebuchadnezzar, as compared with that former one under Shalmaneser.