Original: The Armero tragedy, as the event came to be known, was the second-deadliest volcanic disaster in the 20th century, being surpassed only by the 1902 eruption of Mount Pelée, and is the fourth-deadliest volcanic eruption in recorded history.
Simplified: This was the second deadliest volcanic disaster in the 20th century, ousted only by the 1902 eruption of Mount Pelee, and the fourth deadliest eruption in recorded history.