Jamieson, Fausset and Brown on Micah 1:4

4. Imagery from earthquakes and volcanic agency, to describe the terrors which attend Jehovah's coming in judgment (compare Jud 5:5). Neither men of high degree, as the mountains, nor men of low degree, as the valleys, can secure themselves or their land from the judgments of God.

as wax--(Psa 97:5; compare Is 64:1-3). The third clause, "as wax," &c., answers to the first in the parallelism, "the mountains shall be molten"; the fourth, "as the waters," &c., to the second, "the valleys shall be cleft." As wax melts by fire, so the mountains before God, at His approach; and as waters poured down a steep cannot stand but are diffused abroad, so the valleys shall be cleft before Jehovah.