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The eruption of Mount Pinatubo (General information (It was a stratovocano…
The eruption of Mount Pinatubo
General information
It was a stratovocano
Mount Pinatubo is in Philippines
Occurred on June 15 1991
The second largest volcano eruption in the 20th century
So much magma was removed that the summit collapsed to form a large volcanic depression 2.5 kilometers across
Mount Pinatubo is one of a chain of volcanoes known as the Luzon volcanic arc
Impacts
Economic
Because this climactic eruption was already expected, almost $250 million in property was saved
Commercial air flights were warned about the possibility of the interfering of ash clouds so as a result of that, $100 million was sustained and most equipment was successfully protected
Structures on the two largest US military bases (Clark Air Base and Subic Bay Naval Station) in the Philippines were badly damaged by ash from the volcanic eruption
800 square kilometres of agricultural land was destroyed
650,000 losses of jobs
48% of farmland and crops destroyed causing food shortages
Social
The forecast of the eruption saved 5000 lives
The eruption changed the face of the home of 3 million people, Central Luzon
Nearly 20,000 indigenous Aeta highlanders who lived on the slopes of the volcano, had their homeland completely taken away and destroyed. They are still waiting for resettlement camp
About 200,000 people evacuated the lowlands, after coming back, they still feared the destructive mudflow from the eruption (called lahars) that had already buried towns
Agricultural problems caused starvation and even deaths
847 deaths
1.2-1.4 million homeless
500 died from measles
12,000 injured
Environmental
Almost 20 million tonnes of sulphur dioxide was released into the atmosphere
Due to the sulphur dioxide dispersing throughout the globe, global temperatures temporarily dropped by about by about 0.5°C
Large amounts of searing hot ash, gas, and pyroclastic flows moved in avalanches to fill valleys with deposit as much as 200m thick
How the volcano erupted
This was a cataclysmic eruption, this means that it was very violent and destructive
From June 7 to 12, the hot magma started to reach the surface of Pinatubo
The gas in the magma was almost all gone, so when the magma started oozing out, it formed a lava dome
On June 12, gas charged magma exploded and this was the first eruption of the volcano, Mount Pinatubo
Even more highly gas charged magma reached Pinatubo's surface on June 15 exploded in a cataclysmic reaction the let out more than 5 cubed km of material
Much weaker eruptions were still occurring occasionally until early September
Formation of the volcano
Mount Pinatubo lies between the (continental) Eurasian plate and the (oceanic) Philippine plate
Since it's a volcano (and lies between oceanic and continental plates), this shows that it lies at a destructive plate boundary
The plates both move towards each other due to convection currents. They then collide and an earthquake occurs
Since the oceanic plate is more dense, it subducts under the lighter oceanic plate and moves deeper into the mantle and melts
Extra magma (replaced by the oceanic plate) seeps through crusts and creates volcanic cones