The Arenal Volcano experienced a series of large eruptions on Tuesday afternoon, May 5, 1998. The first ratchet eruption was recorded at 1:05 p.m. when part of the northwest wall of the crater fell apart. Large amounts of lava, rocks, and ash flew out of the volcano during this explosion. Another eruption took place at 2:20 p.m. with material emerging from the same part of the volcano.