Deck 5c - Tectonics: Mt.Pinatubo, Philippines

Question 1

What year was the Mount Pinatubo eruption?

Answer 1

1991

Question 2

What hazards were caused by the Mount Pinatubo eruption?

Answer 2

Large ash plume, sulphur dioxide, pyroclastic density currents, lahars

Question 3

What other natural hazard occurred on the same day as the Mount Pinatubo eruption?

Answer 3

Typhoon Yunya struck the island brining heavy rain and flooding which mixed with the ash deposits causing lahars.

Question 4

What type of plate boundary is Mount Pinatubo on and which tectonic plates are involved?

Answer 4

Destructive- Philippine oceanic plate subducting beneath the continental Eurasian plate. 1991 eruption was triggered by a 7.3MMS earthquake

Question 5

What type of volcano is Mount Pinatubo?

Answer 5

Composite

Question 6

What sort of magma does Mount Pinatubo produce and what sort of eruptions does this lead to? Why?

Answer 6

Explosive eruptions due to higher silica content in the andesitic magma.

Question 7

How frequently does Mount Pinatubo erupt?

(FREQUENCY)

Answer 7

Every 400-500 years

Question 8

What was the VEI of the Mount Pinatubo eruption?

(MAGNITUDE)

Answer 8

VEI = 6

Question 9

What was the duration of the Mount Pinatubo eruption?

(DURATION)

Answer 9

Lasted 9 hours on 15th June 1991

Question 10

What signs were there before the Mount Pinatubo eruption occurred?

(PREDICTABILITY)

Answer 10

Seismic data recorded large earthquakes in 1990, increasing levels of sulphur dioxide released, lava dome grew beneath the surface changing the shape of the volcano

Question 11

How quickly did the Mount Pinatubo eruption occur?

(SPEED OF ONSET)

Answer 11

Very rapid release of ash cloud that reached 22km into the sky producing 5 cubic kilometres of material. Pyroclastic flows reached over 100km/hour

Question 12

What area did the Mount Pinatubo eruption impact?

(AREAL EXTENT)

Answer 12

125,000 km2 are covered in ash. Larger material was deposited closer to the volcano

Question 13

What was the GNI of the Philippines before the Mount Pinatubo eruption?

(ECONOMIC vulnerability)

Answer 13

$830 per capita in 1990

Question 14

What was the level of technology available in the Philippines during the Mount Pinatubo eruption?

(ECONOMIC vulnerability)

Answer 14

Philippine Institute of Volcanology and Seismology (PHIVOLCS) is a national institute set up in 1982 to monitor tectonic hazards to help prepare the population for hazards.

Question 15

How educated were the Philippine population about the risks of volcanic eruptions prior to the Mount Pinatubo eruption?

(SOCIO-ECONOMIC vulnerability)

Answer 15

Government spending on education is low compared to other nearby countries and countries with a similar GNI. Most children attend free schools but quality of education in public schools remains poor.

Question 16

What was the population structure of the Philippines before the eruption?

(SOCIAL vulnerability)

Answer 16

-Youthful population with 41% aged 15 or under
-47.5% of population is urban
-Population density is 368 per km2

Question 17

How stable is the Philippines government?

(POLTICAL vulnerability)

Answer 17

Democratic government with a president that is directly elected by the population. Tectonic hazard preparedness is a key priority for the government.

Question 18

What were the economic impacts of the Mount Pinatubo eruption

Answer 18

-$700 million damages
-1.2 million homes destroyed alongside key infrastructure
-16 commercial aircraft had been damaged by the ash cloud and the airport closed
-Farmland was destroyed by ash

Question 19

What were the social/demographic impacts of the Mount Pinatubo eruption?

Answer 19

-Over 400 people died in the eruption including 300 from failing roofs and 100 from lahars
-Central Luzon home to 3 million people severely damaged
-Disease broke out in evacuation camps
-Many schools were destroyed halting education
-20,000 indigenous Aeta highlanders who lived on the slopes were displaced

Question 20

What are the environmental impacts of the Mount Pinatubo eruption?

Answer 20

-Sulphur dioxide caused acid rain which killed ecosystems
-Eruption created a huge crater that has filled with water and is now known as Lake Pinatubo
-Ash was blown in all directions over long distances destroying ecosystems
-20 million tonnes of sulphur dioxide injected into the atmosphere cooling global temperatures by 0.5 degrees Celsius

Question 21

How prepared was the Philippines for the Mount Pinatubo eruption?

Answer 21

-75,000 people evacuated due to accurate predictions
-US Geological Service put monitoring in place on 3rd April helping to predict the eruption
-Alert put in place to warn of eruption including TV broadcasts
-Dikes and dams constructed in 1991 to control lahars

Question 22

What was the response (short term) to the Mount Pinatubo eruption?

Answer 22

-Refugee and emergency camps set up with 100,000 in 100 camps
-Aid received from countries such as USA and NGO’s including the Red Cross which provided food and blankets
-US Geological Service personnel helped to advise the community and government for 8 weeks following the eruption

Question 23

What was the recovery (long term) to the Mount Pinatubo eruption?

Answer 23

-Long term aid provided
-President Ramos created the Mount Pinatubo Commission to raise 10 billion Filipino pesos in aid
-Resettlement for Aetas and lowlander individuals
-US aid provided $375,000 for relief and rehabilitation projects

Question 24

What was the mitigation after the Mount Pinatubo eruption?

Answer 24

-New homes built on stilts so future lahars would not bury them
-Prediction and measurement of potential future tectonic events improved