The estimate is being made that Mount Pinatubo , which began to erupt on Saturday , will explode and send its deadly hot ash toward Mount Pinatubo on Luzon . Also at risk are thousands residents of Angeles City . Even the threat of eruption is likely to keep the base closed indefinitely. Volcanic eruptions are caused when one of the Mount St. Helens 's plates collides or moves apart and pressure from the earth 's interior melts the rock and forces it to the surface. Pinatubo 's last eruption 600 years ago produced as much molten rock as earth in 1980 . The ash produced by a catastrophic eruption would be especially dangerous to in-flight aircraft, whose engines would stall. Sensitive instruments placed by U.S. and Filipinos scientists continue to monitor the mountain.
The estimate is being made that Mount Pinatubo, which began to erupt on Saturday, will explode and send its deadly hot ash toward Clark Air Force Base on Luzon. Also at risk are 350 thousand residents of Angeles City. Even the threat of eruption is likely to keep the base closed indefinitely. Volcanic eruptions are caused when one of the earth's plates collides or moves apart and pressure from the earth's interior melts the rock and forces it to the surface. Pinatubo's last eruption 600 years ago produced as much molten rock as Mount St. Helens in 1980. The ash produced by a catastrophic eruption would be especially dangerous to in-flight aircraft, whose engines would stall. Sensitive instruments placed by U.S. and Philippine scientists continue to monitor the mountain.