Mount Pinatubo (LEDC)
Causes
The Pacific plate, which is an oceanic plate (a plate underneath an ocean or sea), moves westward towards the Eurasian plate, which is a continental plate (a plate underneath land), and is forced downwards. This is called a destructive boundary, where an oceanic plate clashes with a continental plate, and the oceanic plate is forced down (because it is lighter). The volcano is slightly offset from the plate boundary as when the oceanic plate is subducted, it is melted and forced away, by molten magma, due to the high pressures exerted upon it. It then resurfaces as the density of the molten magma becomes lower than that of the rock, and so it pushes up through the small cracks and explodes through the volcano.
Timeline
July 16 1990 - June 6 1991
A magnitude 7.8 earthquake hits 100km northeast of Mount Pinatubo. Earthquakes occur more frequently around Mount Pinatubo, and small eruptions occur. Scientists start to monitor the area.
June 7 1991
A staggering 1500 earthquakes strike Mount Pinatubo on this day. An eruption of ash sends a plume to 8 km altitude. A new lava dome (when magma forms a circle around the crater) forms 1 km northwest of the main crater.
June 9 1991 - June 14 1991
The lava dome becomes unstable and creates the first pyroclastic flows (a lot of ash, lava and gases ejected from a volcano while flowing very fast), accompanied by larger ash eruptions. By June 14th, the ash cloud has risen to 21 km.
June 15 1991
While typhoon Yunya passes 100 km northeast of Mount Pinatubo, causing heavy rainfall and lahars racing down valley of the volcano, the largest explosion starts in the early afternoon at 3:39 pm. It lasts 9 hours. The eruption column reaches an incredible 35 km height, and spreads out in the stratosphere.
The Pacific plate, which is an oceanic plate (a plate underneath an ocean or sea), moves westward towards the Eurasian plate, which is a continental plate (a plate underneath land), and is forced downwards. This is called a destructive boundary, where an oceanic plate clashes with a continental plate, and the oceanic plate is forced down (because it is lighter). The volcano is slightly offset from the plate boundary as when the oceanic plate is subducted, it is melted and forced away, by molten magma, due to the high pressures exerted upon it. It then resurfaces as the density of the molten magma becomes lower than that of the rock, and so it pushes up through the small cracks and explodes through the volcano.
Timeline
July 16 1990 - June 6 1991
A magnitude 7.8 earthquake hits 100km northeast of Mount Pinatubo. Earthquakes occur more frequently around Mount Pinatubo, and small eruptions occur. Scientists start to monitor the area.
June 7 1991
A staggering 1500 earthquakes strike Mount Pinatubo on this day. An eruption of ash sends a plume to 8 km altitude. A new lava dome (when magma forms a circle around the crater) forms 1 km northwest of the main crater.
June 9 1991 - June 14 1991
The lava dome becomes unstable and creates the first pyroclastic flows (a lot of ash, lava and gases ejected from a volcano while flowing very fast), accompanied by larger ash eruptions. By June 14th, the ash cloud has risen to 21 km.
June 15 1991
While typhoon Yunya passes 100 km northeast of Mount Pinatubo, causing heavy rainfall and lahars racing down valley of the volcano, the largest explosion starts in the early afternoon at 3:39 pm. It lasts 9 hours. The eruption column reaches an incredible 35 km height, and spreads out in the stratosphere.
Social Impacts
The Mount Pinatubo eruption killed around 800 people. Around a 100 people were killed due to lahars, while huge refugee camps were set up and diseases spread rapidly in them (especially diarrhea, chickenpox and malaria) leading to an additional 600 deaths. Around 75,000 houses were damaged or destroyed by the ash, leaving many homeless. Many schools collapsed under the weight of the ash. The ash destroyed all the rice crops, the main source of food for many, leading to food shortages and starvation. Many refugees migrated to urban areas to seek food and shelter.
Economic Impacts
Many factories were destroyed by the ash, meaning that many people lost their jobs which they needed to provide food for their families. Houses and bridges were destroyed too, so people had no shelter and transport was . Manila airport, the Philippines most popular airport, had to be closed due to poor visibility. This would have limited visitors to the islands. Over 1 million farm animals died due to either starvation or drinking contaminated water. This had a massive economic cost. 650,000 people lost their jobs. The total cost of damages and repairs was an estimated $450 million.
Environmental Impacts
The eruption sent a cloud of steam that rose 31 km into the sky, turning day into night. Many volcanic bombs (a large piece of molten rock) were thrown into the air. 50 cm of ash fell on nearby farmland; some ash reached Australia. The typhoon Yunya caused rain to mix with ash forming dangerous lahars, eroding rivers and reached Angeles City, 20 km away. Water supplies were contaminated with ash and poisonous gases, making it dangerous for humans and animals alike to drink water.
The Mount Pinatubo eruption killed around 800 people. Around a 100 people were killed due to lahars, while huge refugee camps were set up and diseases spread rapidly in them (especially diarrhea, chickenpox and malaria) leading to an additional 600 deaths. Around 75,000 houses were damaged or destroyed by the ash, leaving many homeless. Many schools collapsed under the weight of the ash. The ash destroyed all the rice crops, the main source of food for many, leading to food shortages and starvation. Many refugees migrated to urban areas to seek food and shelter.
Economic Impacts
Many factories were destroyed by the ash, meaning that many people lost their jobs which they needed to provide food for their families. Houses and bridges were destroyed too, so people had no shelter and transport was . Manila airport, the Philippines most popular airport, had to be closed due to poor visibility. This would have limited visitors to the islands. Over 1 million farm animals died due to either starvation or drinking contaminated water. This had a massive economic cost. 650,000 people lost their jobs. The total cost of damages and repairs was an estimated $450 million.
Environmental Impacts
The eruption sent a cloud of steam that rose 31 km into the sky, turning day into night. Many volcanic bombs (a large piece of molten rock) were thrown into the air. 50 cm of ash fell on nearby farmland; some ash reached Australia. The typhoon Yunya caused rain to mix with ash forming dangerous lahars, eroding rivers and reached Angeles City, 20 km away. Water supplies were contaminated with ash and poisonous gases, making it dangerous for humans and animals alike to drink water.