Torres opened the scoring in just the 4th minute, with a powerful finish on the angle from 10 yards out, and Spain dominated the rest of the first half without finding another goal.
David Silva's composed finish just after halftime doubled the advantage, and Torres grabbed the 3rd goal slotting past Given after a quick break. Substitute Cesc Fabregas drove in a fourth goal in the 83rd minute to complete the scoring in a one-sided game.
The victory was enough to move Spain above Croatia to the top of Group B on goal difference, but these two sides face each other on Monday, and are both sides will still need at least a point in order to progress.
Meanwhile, Ireland have been eliminated, and will play Italy on Monday, with the Italian side needing a win, and in fact needing a 3+ goal victory to be sure of progressing.
Spain 4 (Torres 4, 70, Silva 49, Fabregas 83)
R. of Ireland 0
Video from UEFA.com of goals from Spain v Republic of Ireland