Definition of "Eruption" :

noun: the emergence of a tooth as it breaks through the gum

noun: a sudden very loud noise

noun: a sudden violent spontaneous occurrence (usually of some undesirable condition)

noun: the sudden occurrence of a violent discharge of steam and volcanic material

noun: (of volcanos) pouring out fumes or lava (or a deposit so formed)

noun: symptom consisting of a breaking out and becoming visible