mount pinatubo Flashcards
1
Q
background info?
A
- A composite volcano on the island of Luzon in the Philippines (subductive plate boundary)
- After more than 600 years of inactivity, it erupted again on 12 June 1991
- It has andesitic lava, relatively thick and full of gas, causing explosive eruptions. A cloud of steam and ash was sent 30km up into the atmosphere, and pyroclastic flows descended from the crater at speeds of more than 200km an hour.
2
Q
primary impacts?
A
- Many people were able to evacuate, as the eruption had been predicted and advance warning was sent out. However, the eruption still caused serious damage.
- 847 people were killed in the main eruption, many by pyroclastic flows and ash falls.
- The ash cloud caused the region to become cold and dark, hampering rescue operations.
- 5000 homes were destroyed and a further 50,000 damaged. Typhoon Yunya struck at the same time as the eruption. Torrential rain caused much of the ash to be washed from the Earth as mud, causing buildings to collapse under the weight.
- Many people were displaced to shanty twins on the edge of Manila, the capital city or to evacuation camps.
- Power supplies were cut, and roads and bridges were left unusable, and the water supply quickly became contaminated.
3
Q
secondary impacts
A
- As winds dispersed the gas cloud (10 million tonnes of sulfur dioxide), global temperatures dropped temporarily (1991-1993) by 0.5 degrees Celsius.
- Hundreds of people died from disease (measles, pneumonia and diarrhea) in the evacuation camps.
- Crops were destroyed as ash covered 800 km squared of rice fields, and around 800,000 farm animals were killed, with the cost to farmers estimated at 1.5 billion pesos (around 20 million pounds)
- Devastating lahars up to 3m high
After many buildings were destroyed, the US Air Force base at Pinatubo closed and relocated to Singapore. Many Filipinos lost their jobs and local trade suffered great losses.
4
Q
immediate response
A
- The Philippine Institute of Volcanology and Seismology detected swarms of earthquakes beneath Pinatubo in March 1991 indicating that magma was on the move.
- Helicopters with gas monitoring equipment flew over the crater daily, and geologists mapped the distribution of lahar deposits from previous eruptions in order to better decide which areas should be evacuated.
- Warnings were issued and local people evacuated to camps set up in advance. Vaccinations were given to try to combat the threat of measles and flu. International emergency aid was provided both after the eruption and the lahars.
5
Q
long term management
A
- Building dykes and dams to protect against lahars and flash floods
- Establishing new farms and employment away from the danger area, including converting the abandoned US air base into Clark International Airport, where tax free trading attracts businesses which now employ over 47,000 people.
- Creating new towns and villages outside the area of risk.
