Mount Pinatubo
- Created by: ofields755
- Created on: 15-01-16 09:22
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- Predicting the 1991 eruption of Pinatubo - Luzon Philippines
- History
- Last Erupted C14th - no written record
- Last one - 600 years ago
- study of deposits and flows of pyroclastic material showed it had only erupted 4/5 times in 2 millennia
- infrequent events
- First Signs
- July 1990 - EQ of 7.7 and killed 1600 people
- After EQ, pacific plate melted forming extra magma - rose from the asthenosphere into large magma chamber
- resulted in Mount Pinatubo
- After EQ, pacific plate melted forming extra magma - rose from the asthenosphere into large magma chamber
- after the EQ
- 2nd April 1991 - changes in Pinatubo (after being dormant for 600 years)
- Steam came out of the side vents on flanks (side)
- Officials were brought in
- Contracted USGS
- to protect 2 military facilities
- Naval base - Subic Bay and Clark Air force base
- to protect 2 military facilities
- Aerial Survey
- Portable Seismometer installed - 400 EQ in 2 days
- From Philippine Insitute of Volcanology and Semisology
- Contracted USGS
- 2nd April 1991 - changes in Pinatubo (after being dormant for 600 years)
- July 1990 - EQ of 7.7 and killed 1600 people
- Next 7 Weeks
- Dismissed steam released
- Seismic monitoring
- USGS - network of seismometers
- EQ - 8km below 40-150 per day
- Not usually high number - but spread over 5-6km
- EQ - 8km below 40-150 per day
- 3d view of what happening below the surface
- USGS - network of seismometers
- Set up HQ at Clark air base
- Gas emissions
- Helicopters- gas samples using correlation spectomemeter
- Recorded SO2 levels - 500 tonnes per day - 5 weeks = 5,000 per day
- Helicopters- gas samples using correlation spectomemeter
- Visual Observations
- plane and helicopter
- recorded the steam emissions and surface changes
- 3 June - largest tremors
- 20,000 people evacuated in 10 km
- Issues a level 2 alert
- 15,000 personnel at Clark air base = prepare to leave at short notice
- 5 June
- EQ beneath central zone
- Sulphur Dioxide levels falling
- suggested magma retaining as gas content = explosive
- 7th June
- increasing activity
- 120,000 people within 18km evacuated to temp centres
- Level 4 Alert
- Air force remained but on alert
- meanwhile - Japan volcano erupted - more violent that predicted
- 6,000 people evacuated and saved - 34 died
- 8-9 June
- 48 hours later - first major eruption
- 60km danger zone - 300,000 people evacuated
- level 5 alert
- air base evacuated (4,000 moved to safe distance)
- Dome of lava from air
- matched previous deposits
- confirmed explosive nature
- matched previous deposits
- History
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