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Mount Pinatubo 1991
The secondlargest volcanic eruption of this century, and by far the largest eruption to affect a
densely populated area, occurred at Mount Pinatubo in the Philippines on June 15, 1991. The
eruption produced highspeed avalanches of hot ash and gas, giant mudflows, and a cloud of
volcanic ash hundreds of miles across. The impacts of the eruption continue to this day.
Population of 93 million
In the Cabusilan Mountain range on the island of Luzon in the Philippines. It is just north of
the capital city Manila.
NIC country exporting products around the
Mountainous islands of which there are 7,107
The country is not only affected by earthquakes
and volcanoes but also by tropical storms
Life expectancy is 71
500,000 people within 40km of the volcano
and 100,000 on the flanks
Lots of rivers have their source on Pintubo
Area surrounding is excellent for rice growing
Tectonic Background
It is part of the pacific ring of fire.
Mt. Pinatubo is a typical island arc volcano. These are composite volcanoes characterized
by long dormant periods punctuated by intense explosive eruptions of variable intensity and
Had not erupted since 1380
Located at destructive boundary between the Eurasian and Philippines plate where the
Philippines plate is being subducted as it is oceanic.
Mt. Pinatubo was formed by the Eurasian Plate subducting beneath the Philippine plate,
along the Manila trench.
Several important river systems have their sources on Pinatubo.
It is 87km NW of Manila.
The US Clark Airbase (less than 5km
from Angeles City population of around
250,000 in 1991) is 14km W of the

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Volcanic events
June 1991 ­ Eruption lasted 1 week. VEI was 6 (these eruptions have profound long term
effects on the surrounding area and noticeable short term effects on global climate.) The
volcano had not erupted in the last 600 years.
9th June ­ First day of eruptions. (level 5 alert)
12th June 3 major explosions and seismic activity. Material ejected 25km high
13th June ­ heavy ash blown hundreds of km west.
14th June ­ Pyroclastic flows affect areas 15 km away.…read more

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Short Term
800 people killed 300 by collapsing roofs and 100 by lahars(including some Aeta who
refused to move from their `holy mountain'. (Many of these deaths were not immediate.)
2 million houses, a hospital, schools, factories were covered in ash.
Hundreds of people had to flee to cities for food and shelter.
2.1 million people were affected by the eruption.
Power supplies were cut for 3 weeks.
Relief work was made more difficult by ash covering roads and lahars damaging bridges.…read more

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Agriculture was heavily disrupted, with 800 square kilometres (200,000 acres) of
ricegrowing farmland destroyed, and almost 800,000 head of livestock and poultry killed,
destroying the livelihoods of thousands of farmers. The cost to agriculture of eruption effects
was estimated to be 1.5 billion pesos.
Short Term
200,000 buildings were destroyed ­cost of rebuilding was great.
There was disruption to work, loss of jobs, food shortages....
80,000 hectares of farmland was buried under ash.
Livestock deaths were 800,000 ­ overall cost to agriculture ­ 1.…read more

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Land use planning and science and technology were also essential
Initial response included evacuation and warning systems being used to remove people from
the danger zones which saved numerous lives.…read more

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It erupts much more frequently than composite cone volcanoes like Pinatubo
Tectonic Background
Located on a destructive plate margin between the African and Eurasian plates
Northern edge of the African plate is being subducted
The eruption in 1991 started on 14th December and last for 435 days which was the most
volumous eruption from Etna in 300 tears
The lava flowed down the SE flank of the volcano into the Valle del Bove
The acidic lava had a low effusion rate which posed very little…read more

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The authorities then decided to try and block off the lava flow and did this by dropping
concrete blocks into the crater using helicopters.…read more

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The lava had to flow more than 8 km before it
became a serious threat.
· The possibility of diverting the lava flow into uninhabited areas (at least 7 km from the
nearest village).
2002 Eruption ­ Causes
Composite or strato volcano active
Series of earthquakes throughout November 2002
Clouds of pyroclastic gas and ash from two vents.
Magma thrown 100m into air.
Lava runs down volcano side in two separate flows.
Ash continued to fall on city of Catonia.…read more

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Airport at Catonia closed for 4 days.
Ski resorts destroyed as well as a restaurant.
Hundreds of acres of forest destroyed
Eruption 2002 ­Responses
State of emergency declared.
Attempts to divert lava flow away from scientific
monitoring equipment.
Army used bulldozers to build barriers and create channels
for lava flow away from populated areas.
Medical ship sent by government for emergencies.
Tax breaks for villagers, £5.6 m in immediate assistance.…read more


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