40 Fun Facts About Mount Pinatubo

What killed most of the people who died in Mount Pinatubo's 1991 eruption, despite mass evacuations?

Collapsing roofs caused most of the deaths, because ash soaked by heavy rain grew far too heavy for buildings to bear. Lava played no part.

Which natural disaster struck on the same day as Mount Pinatubo's climactic eruption in June 1991?

A typhoon named Yunya struck that same day, turning the falling ash into a heavy rain of mud, while its winds flung ash in every direction.

What happened to average global temperatures in the two years after Mount Pinatubo's 1991 eruption?

They dropped about 0.5 °C, because a haze high in the atmosphere bounced sunlight back into space. The chill lasted from 1991 through 1993.

How long had Mount Pinatubo been dormant before it reawakened with steam blasts in April 1991?

About 500 years of quiet had let lush vegetation hide the volcano so well that most people living nearby knew nothing of its violent past.

Which US Air Force site, 14 km east of Mount Pinatubo's summit, was abandoned after the eruption?

Clark Air Base was handed back to the Philippines in November 1991, after ash wrecked its buildings and mudflows swept across its grounds. It later became an international airport and freeport zone.

How does the 1991 eruption rank against Mount Pinatubo's earlier eruptions in the geologic record?

Among the smallest, remarkably: the eruption that gave birth to the modern volcano is estimated to have been five times larger than the one in 1991.

What nickname was given to the June day when Mount Pinatubo's ash brought 36 hours of darkness?

Black Saturday saw an ash cloud more than 300 miles across turn day into night, while wet ash settled over the land like heavy grey snow.

Mount Pinatubo's eruption was about ten times larger than the 1980 blast from which US peak?

St. Helens was dwarfed: the Philippine blast threw out over ten cubic kilometres of ash and rock, ranking second among all eruptions of the 20th century.

What did friction inside Mount Pinatubo's rising ash column generate in abundance in June 1991?

Lightning flashed through the plume as colliding ash particles built up electric charge, even while the column climbed 24 km above the summit.

Pinatubo sent more particles into the upper atmosphere than any eruption since which 1883 disaster?

Krakatoa had held that mark for over a century; satellites tracked the 1991 cloud several times around the globe, and its haze lingered for three years.

On which Philippine island does Mount Pinatubo stand, about 87 km northwest of the capital, Manila?

Luzon is also home to Manila, and about six million people live close to the volcano, which rises at the point where three provinces meet.

Which gas, nearly 20 million tons of it, did Mount Pinatubo blast high into the atmosphere in 1991?

Sulfur dioxide turned into a haze of tiny acid droplets that circled the Earth in about three weeks and covered the whole globe within a year.

What name is given to the volcanic mudflows that buried towns around Pinatubo for years after 1991?

Lahars form when heavy rain washes loose ash downhill; they can race along at 65 km per hour, and here they did more damage than the eruption itself.

What landform, 2.5 km wide, was left when Mount Pinatubo's summit collapsed in the 1991 eruption?

A caldera formed because so much magma drained from beneath the peak that it caved in, leaving the mountain about 260 m shorter than before.

Mount Pinatubo's 1991 ash cloud rose about 35 km, punching into which layer of the atmosphere?

The stratosphere received the cloud, and the haze that formed there gradually spread around the entire planet over the following year.

Which US agency helped Filipino scientists forecast Pinatubo's 1991 eruption and save thousands?

The US Geological Survey flew in portable instruments, and the joint team's warnings cost under $1.5 million while sparing at least 5,000 lives.

The lake that filled Mount Pinatubo's new crater after 1991 was at first hot and highly what?

Acidic water with a pH as low as 2 and a temperature near 40 °C slowly mellowed as years of monsoon rain diluted and cooled the lake.

Mount Pinatubo's first big explosive eruption came on June 12, 1991, which Philippine holiday?

Independence Day in 1991 brought an ash column 19 km high, the opening act of a climax that followed three days later.

What type of volcano is Mount Pinatubo, the same steep, explosive kind as Italy's Mount Etna?

Stratovolcano magma is thick and sticky, so gas cannot escape easily and pressure builds until the mountain blows apart instead of oozing lava.

Mid-latitude levels of which atmospheric gas fell to record lows after Pinatubo's 1991 eruption?

Ozone was destroyed at a much faster rate after the eruption, and in 1992 the hole over Antarctica grew to the largest size recorded up to then.

Which indigenous people, driven from Pinatubo's slopes in 1991, won title to the summit in 2010?

The Aeta numbered about 20,000 on the mountain, and all but about 20 were led to safety before the eruption wiped out their villages.

Mount Pinatubo rises where Pampanga and Tarlac meet which third province, home to the crater lake?

Zambales also lends its name to the mountain range the volcano belongs to, a chain running down the western side of the island.

Which US naval station south of Mount Pinatubo was blanketed in ash and handed back in 1992?

Subic Bay became the escape route: warships sailing from the port carried thousands of evacuees to Cebu, the first leg of their journey home.

Who was president of the Philippines when Mount Pinatubo erupted, a year before leaving office?

Corazon Aquino faced the eruption eleven months after a magnitude 7.8 earthquake, in the middle of a national debate over keeping US military bases.

Which sky events looked far darker than usual in the year after Mount Pinatubo's 1991 eruption?

Lunar eclipses normally leave a dimmed Moon in view, but dust in the atmosphere absorbed so much sunlight that the eclipsed Moon was hardly visible at all.

Which US island territory received most of the American evacuees fleeing Mount Pinatubo in 1991?

Guam's Andersen Air Force Base processed the vast majority of the roughly 20,000 evacuees before they flew on to the continental United States.

The name Pinatubo may carry which meaning in Tagalog, perhaps a folk memory of an old eruption?

Made to grow, or a fertile place where one can raise crops, is how the word can be read, which may hint at knowledge of an eruption around 1500.

Why did farmers near Mount Pinatubo switch to peanuts, cassava and sweet potatoes after 1991?

They ripen quickly, so the harvest could be brought in before late-summer rains sent fresh mudflows across the fields.

In a Pinatubo legend, the fire-breathing sea spirit Bacobaco could change into which animal?

A huge turtle was his other form; chased by spirit hunters, he dug a great hole in the summit and showered the land with rock, mud and fire for three days.

Which Philippine president died in 1957 when his plane, named Mt. Pinatubo, crashed in Cebu?

Ramon Magsaysay named his presidential C-47 after the then-quiet volcano; the plane struck Mount Manunggal, killing him and 24 others on board.

What was the code name for the US evacuation of about 20,000 people from bases near Pinatubo?

Operation Fiery Vigil moved service members and their families out by sea and air in June 1991, and very few of them ever returned.

Which mountain city was devastated by the 1990 earthquake that may have helped wake Mount Pinatubo?

Baguio lies about 80 km from the volcano, where the magnitude 7.8 shock set off a landslide and a brief burst of steam.

What were engineers drilling for on Pinatubo until 1990, in wells given up just before it awoke?

Geothermal heat proved disappointing and the project was abandoned 13 months before the first blasts; some indigenous elders said the drilling had angered the mountain's deity.

How did authorities lower the lake in Mount Pinatubo's crater in 2001, fearing a collapse?

Workers cut a notch in the rim and drained about a quarter of the water, after some 9,000 people nearby had been evacuated in case of a flood.

What kind of sports venue in Quezon City sheltered some 30,000 people who fled Pinatubo in 1991?

A velodrome, the Amoranto cycling track, became a vast camp as most of the 60,000 people who left the danger zone headed for Metro Manila.

Which wide-body airliner was pictured tipped onto its tail by the weight of Mount Pinatubo's ash?

A DC-10 sat back on its tail under the ash, while at least 16 airliners flew into the drifting cloud and ten of their engines had to be replaced.

Which Pampanga town's San Guillermo church was half-buried by a mudflow from Mount Pinatubo in 1995?

Bacolor saw 18 of its 21 villages buried, as flows between 1991 and 1995 raised the ground across the town by about six metres.

Which deity do indigenous elders say dwells on Mount Pinatubo and caused the 1991 eruption in anger?

Apo Namalyari, whose name means lord of happenings, was said to be angered by illegal loggers and by engineers drilling deep wells into the mountain.

Which PHIVOLCS chief led the warnings before Pinatubo erupted and died in a 2005 helicopter crash?

Raymundo Punongbayan ran an information campaign that persuaded nearby communities the danger was real, an effort credited with saving thousands of lives.

Which volcanic rock, laced with the unusual mineral anhydrite, dominated what Pinatubo threw out?

Dacite and andesite also built the ancestral volcano on the same spot, whose eruptions were far less explosive than the modern mountain's.