When Mount Pinatubo first began to smoulder two months ago , seismologists began to climb over the mountain and place their recording devices at strategic points . Increasing levels of the gas may signal an impending eruption. Pinatubo had a habit of exploding with a force twice as great as Mount St. Helens . After a few weeks of investigation , the scientists decided to recommend evacuation of 84,000 people . The evacuation was timely . The mountain erupted blowing hot ash and pumice 80,000 feet into the air . This was a turning point in successful volcanic forecasting . Government officials , however , believe that the damage at Clark Air Base will force the permanent closure of the base .
When Mount Pinatubo first began to smoulder two months ago , seismologists began to climb over the mountain and place their recording devices at strategic points . Pinatubo had a habit of exploding with a force twice as great as Mount St. Helens . After a few weeks of investigation , the scientists decided to recommend evacuation of 84,000 people . The evacuation was timely . The mountain erupted blowing hot ash and pumice 80,000 feet into the air . This was a turning point in successful volcanic forecasting . Government officials , however , believe that the damage at Clark Air Base will force the permanent closure of the base .