The eight successful excavations with this card's effect can deal a total of 4000 damage, which is the amount of Life Points that Duelists start each game with at the time this card appeared in the Yu-Gi-Oh! anime.
This card's damaging effect is worded as the resolution of a single effect, so by the game rules at the time of this card's release, a player could (and indeed was required to) continue to excavate cards and damage their opponent even after their Life Points had already become 0. This would continue to apply until the March 20, 2015 ruling change on victory conditions in the TCG.
This is based on this card's usage use in the Yu-Gi-Oh! anime, where Yami Yugi continued to attack Weevil Underwood several times using this card, even after Weevil had already lost the Duel.