Mt. Pinatubo

Mt. Pinatubo

1. Background

   • Erupted 15th June 1991
   • VEI 6
   • 2nd largest terrestrial eruption of 20th century
   • Oceanic Phillipines plate subducted Continental Eurasian Plate
   • Typhoon Yunya occurred at same time

2. Preparation

   • 1. USGS & PHIVOLCS responsible for prediction
   • 2. Hazard map with past lahars and pyroclastic flows tracked
   • 3. USGS placed 7 seismographs around the volcano
   • 4. Past eruptions showed explosivity of eruption
   • 5. US airforce took sulphur dioxide samples with spectrometer recording an increase from 500 tonnes/day to 5000 tonnes/day over 5 weeks
   • 6. Earthquakes occurred at a depth of 8km 140/day pre-eruption
   • 7. Small explosions noted April 1991
   • 8. 1st Danger zone of 10km; 20k evacuated from 3rd June
   • 9. Level 5 alert of 120k 20km radius
   • 10. New danger zone of 60km including city of Angeles with pop. approx 400k
   • 11. June 8th-9th Lava dome spotted from air
   • 12. US air and naval bases evacuated involving 100s of thousands of military personnel

3. Costs

   • $1.5m to monitor
   • $40m to evacuate
   • Averted
     • $100m Phillipines Airlines
     • $200m US Airforce

4. Primary Effects

5. Secondary Effects

6. Limitations to prediction

   • A. Typhoon Yunya made prediction difficult
     • increased ash fall & lahars
   • B. LEDC
     • Poor housing & little monitoring
   • C. Illness due to poor sanitations
     • Lack of clean water & medicines
   • D. Lack of Education
     • Locals reluctant to leave

7. Responses

   • Immediate
     • National Disaster Coordinating Council
       • Mobilised aid to evacuation shelters
     • Health Advice to public on dangers of ash particles
     • Disease caused 650/800 deaths
       • Poor conditions
   • Long Term
     • Lahar early warning system in place since 1991
     • Evacuees resettled & 10 billion pesos scheme set up to assist this & infrastructure
     • Engineers failed to trap lahars behind dams
     • Many died from lahars from 1992 to 1994
     • 100k homes destroyed by lahars since 1991