3 Which in the Earth's hollow caves has long been hidden 4 And, shut up fast within her prisons blind,
fast > firmly; closely blind > {Dark, lightless; lacking an opening; secret}
5 Makes the huge element against her kind
huge element > [Earth] kind > nature
6 Move, and tremble as she were aghast,
as > [as though] aghast > terrified
7 Until he an issue forth may find;
issue > outlet
8 Then forth he breaks, and with his furious blast
blast > {Blast; also: blighting wind, breath of a malignant power, as 102.38:6, since it causes the skies to become overcast}