#Throwback On this day in 1991, as the Philippines commemorated Independence Day, Pinatubo Volcano had its first major eruption - sending ash column up to nearly 24 km high! Nearly 48 hours after the government raised the alarm and Clark Airbase evacuated, Pinatubo unleashed its first major fury - proving that the warnings were right. Scientists call this the 'throat clearing' phase of Pinatubo, which preceded its largest eruption on June 15. Here's a video excerpt from the documentary MT. PINAT