ANGELES CITY, Philippines -- Scientists here fear that the worst may be yet to come from the Mount Pinatubo volcano that erupted like an atomic explosion yesterday and again early today, chasing thousands of Filipinos from their homes and Americans from nearby Clark Air Base, one of the largest U.S. military facilities in the world.
The volcano erupted four times yesterday, sending plumes of steam and ash 12 to 15 miles into the sky.
"We think this may not be the main eruption," said Raymond Punongbayan, director of the Philippine Volcanology and Seismographic Institute. "There is a strong probability that another strong eruption will come."
Rain began falling heavily last night, sending huge mud flowand boulders cascading down the volcano's flanks. A road just below the western rim was rendered impassable, and rivers were filled with mudand debris.
Lumps of pumice or rock fell as far as 15 miles away, and there were reports of ash in towns up to 13 miles from the volcano's boiling summit.
Only one death was reported from the eruptions, the largest aPinatubo in more than 600 years. A Filipino serving in the U.S. Navy was killed yesterday when his car skidded on an ash-slicked road north of Subic Bay Naval Base and struck a bus.
Assessing the damage was difficult. The institute said the volcano remained so dangerously active that no one could get closer than 12 miles to inspect it.
Mr. Punongbayan was most alarmed by the possibility of a plinian-type eruption, in which the magma, or molten core of the volcano, rises to the surface and explodes, triggering catastrophic consequences. He said the long-lasting tremors recorded this week indicated that such an eruption may well be under way.
A plinian eruption would be devastating for people near the volcano. It would eject egg-sized rocks, huge amounts of ash and pyroclastic flows -- a substance similar to lava, but thinner, which runs as hot as 600 to 1,000 degrees Celsius and moves at speeds of up to 60 mph.
A plinian eruption would be devastating to Clark as well. "In the worst-case scenario, the base could be buried by pyroclastic flows," he warned. "Any people remaining there will die, buildings will collapse and electronics will be destroyed."
Pyroclastic flows would follow existing channels. There is a river running from Pinatubo to a point close to the base, scientists warn.
In Manila, some politicians raised the possibility of an even greater danger from nuclear weapons that might be stored at Clark. But Lt. Col. Ron Rand, a Clark spokesman, insisted that no such danger existed.
The U.S. government's policy is to neither confirm nor deny thpresence of nuclear materials at any of its military facilities.
A Pentagon spokesman, Air ForceCapt. Sam Grizzle, said that weaponry at the base was being reduced as fighter squadrons were eliminated but that "the ordnance that is there is safe and secure."
About 14,500 Clark military personnel and their families were safely evacuated to the Subic base Monday. About 1,500 staff, mainly police, were left behind to protect the base, but yesterday's eruption sent most of them running for safe ground.
"Everyone panicked when they heard the warning siren this morning," said a guard at Clark's main gate, who evacuated the base, then returned once things quieted down."We were all afraid it would hit the base. It was so big."
Colonel Rand said that the mushroom cloud of ash remained for more than a half-hour before it was blown west toward the South China Sea. "The pillar of ash was the only thing you could see in all directions."
Nearly 35,000 Filipinos have now been evacuated from area within 12 miles of the volcano and from places potentially reachable by flows.
At least 250 tribesmen have refused to leave villages close to Pinatubo because they fear that they will not be able to feed themselves if they leave now, during harvest season.
Aug. 26-28, 1883, Krakatau, Indonesia: An estimated 35,000 deaths
May 8, 1902, Mount Pelee, Martinique: 30,000
Nov. 13, 1985, Nevado de Ruiz, Colombia: 22,940
1669, Mount Etna, Italy: 20,000
79, Mount Vesuvius, Italy: 16,000
1792, Mount Unzen, Japan: 15,000
1169, Mount Etna, Sicily: 15,000
1815, Tamboro, Indonesia: 12,000
1919, Mount Kelud, Indonesia: 5,000
1631, Mount Vesuvius, Italy: 4,000
1772, Mount Papandayan, Indonesia: 3,000
Jan. 18-21, 1951, Mount Lamington, New Guinea: 3,000
1911, Mount Taal, Philippines, 1,400.
#SOURCE: Associated Press