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The Eruption Of Mount Pinatubo in 1991 (The Causes and Continuing…
The Eruption Of Mount Pinatubo in 1991
General Facts On The Eruption
Eruption Took Place on the June 15, 1991
Located on The Cabusilan Mountains (Most Prominent site within the Zambales Mountains) on the island of Luzon, Philippines
Elevation (Height) : 1,486 m
The Eruption was the 2nd biggest in the 20th Century
Mount Pinatubo is an active stratovolcano
Mount Pinatubo is part of a chain of volcanoes which lie along the western edge of the island of Luzon
The Volcano's Geology
It is a Subductive Volcano, which means it is formed by the process in which one plate converges over a less dense one
The Two plates are the Continental Eurasian and Oceanic Philippine plate
The Continental Eurasian is less dense than the denser Oceanic Philippine plate, so it is being pushed under it
Because of that, The Continental plate is being pushed into the mantle, and the heat melts it. That causes an excess in the amount of magma in the mantle, so that increases pressure in the cracks in the ground (The Volcano)
The Causes and Continuing Hazards
Lots of pressure build up in the magma Chamber
From 7 - 12 June, the magma first sweeped up to the surface
However, it lost lots of its gas on its way to the surface, so the built up pressure was reduced
However , on June 12, millions of cubic yards of gas-charged magma reached the surface and exploded
Higher amounts of gas-charged magma exploded and ejected more than a cubic mile of material
Magnitude 5 Earthquake Follows
Not Erupted for 500 years
Earthquakes of magnitudes 2.0 or greater were occurring at the rate of more than 150 per hour
Lots of Volcanic Tremor and Aftershocks
Tremors lasted for the next 10 days
Effects Of The Disaster
Social Effects
50,000 people had to be evacuated from a 30km radius of the volcano
300 people killed due to falling buildings and infrastrucutre
1.2 million people homeless and had to evacuate to places like Manila
Buildings, houses and infrastructure destroyed covered in ash
The "Aeta Tribe " affected the most, because they were living in the mountains near mount pinatubo
Economic Effects
Houses and bridges destroyed and needed replacing and Manila airport had to be closed
Heavy rainfall from typhoon Yunga causes buildings that were already shaken to get damaged further or completely destroyed
Farmland destroyed by falling ash and pumice
1991 harvest was destroyed and 650,000 people lost their jobs
caused havoc to the infrastructure and to economic activities of Central Luzon
454 million pesos ($US 17 million) of business was wasted in 1991
37 million pesos ($US 1.4 million) of business in 1992 wasted again
Damage to crops, infrastructure, and personal property totaled at least 10.1 billion pesos ($US 374 million) in 1991 and an additional 1.9 billion pesos ($US 69 million) in 1992
The pumice and ash disrupted flourishing economy of central Luzon
Environmental Effects
Volcanic ash is blown in all directions over hundreds of KMs, smothering fields and buildings.
Global cooling caused by ash released in the atmosphere of 0.5°C
Fast flowing volcanic mud flows (lahars) cause sever river bank erosion, undercut bridges, and burned land
Lots of ash covered the area near Mount Pinatubo