The main event happened three days later when more than a cubic mile of material exploded out of the ground, the second largest eruption this century.
"Cataclysmic", the United States Geological Survey called it, and you can see why.
The effects were devastating. Large parts of the Pacific island were coated with a thick layer of volcanic dust, while a cloud of ash rose 22 miles into the atmosphere, darkening the skies and causing a major obstacle to commercial aircraft.
The months and years that followed have proved even more damaging. Twenty million tons of noxious sulphur dioxide were discharged into the stratosphere - more than is produced by US industry in a year. Pyroclastic flows - sticky amalgams of hot ash and gas up to 200 metres thick - poured into valleys, solidified and refused to cool down. Some of them still had temperatures of 500'C five years later.
Heavy rains created giant mudflows (lahars) which buried entire towns and villages, rice paddies and sugar cane fields. Around 20,000 Aeta, indigenous people who had lived in the shadow of the volcano for generations, were displaced and still have not returned to their homes.
Satellites tracked the cloud as it circled the world several times, lowering the earth's temperature by about half a degree centigrade over the next two years. Western Europe experienced an unusually mild winter, and there were vivid sunsets the world over. Climatologists have even connected the eruption with the mysterious El Nio weather phenomenon. An umbrella seems like flimsy protection from all that. Harvey McGavin