1. Volcanic Hazards p. 138-140, web reading
Volcano Facts
Volcano Hazards
Fall processes
Flow processes
Other types
Predicting Volcanic Eruptions

2. Giant Caldera Volcano: Yellowstone
Old Faithful
Ground collapse ~ Area of NYC
Material ejected ~1000 km3
Ash Fall

3. Toba, Indonesia The Biggest Eruption?
75,000 years ago

4. Toba, Indonesia The Biggest Eruption?
Caldera diameter 100x35 km
Volume erupted 2,800 km3
10 cm of ash fell in India, 3000 km away
Volcanic winter for a decade
With global cooling 3-5°C
Might have affected human evolution

5. Volcanic Eruptions over the last 10,000 years
1300 active volcanoes
550 eruptions (< 2000 yrs)
<10% potentially destructive volcanoes have been studied in detail
~800 million people risk
>50% of world’s volcanoes in nations with per capita GDP <20% US

6. Volcanic Hazards
Fall Processes
Flow Processes
Web reading

7. Lava Flows Basaltic lava (low viscosity)
Usually slow moving (<10 mph)
Rarely life threatening

8. Nyiragongo volcano, Congo Goma, Jan. 19, 2002
Molten lava flows down a street in the eastern Congolese town of Goma Saturday Jan. 19, More than half of Goma has been consumed by lava forcing several hundred thousand people to flee the city after a nearby volcano erupted on Thursday Jan. 17. (AP Photo/Sayyid Azim)
Congolese residents of Goma watch as part of the main street lies covered in lava, January 19, The Nyiragongo volcano erupted, killing more than 45 people and sending thousands of others fleeing into neighboring Rwanda. REUTERS/George Mulala
Nyiragongo volcano, Congo
Goma, Jan. 19, 2002

9. Nyiragongo volcano, Congo
Goma, Jan. 19, 2002

10. Pyroclastic Flows High density mixture of hot ash, rock, and hot gases
Temp. >500C
Velocity > mph

11. Pyroclastic Flows

12. Mt Unzen, Japan Pyroclastic flows
Eruption in June, 1991, killed 40 journalists and 3 experienced volcanologists
Copy words from Stan’s version

13. Ash Falls (Tephra Falls)
can cover large areas for days to weeks
ash will last on the ground for months to years
making land and water unusable
provide material for future hazards (lahars)
Mount Pinatubo, Philippines June 1991

14. Ash fall in Rabaul, Papua New Guinea, 1994

15. Volcanic Ash–Danger to Aircraft
High-pressure nozzle guide vane assembly removed from Rolls-Royce RB C2-19 after volcanic ash encounter shows heavy deposits of resolidified ash on nozzle guide vane leading edges. This assemblage was removed from the British Airways B-747 that suffered a temporary four-engine flameout after flying through an ash plume from Indonesia's Mt. Galunggung on June 24, 1982.
Volcanic ash can be a serious hazard to aviation even thousands of miles from an eruption. Airborne ash can diminish visibility, damage flight control systems, and cause jet engines to fail USGS
Part of a 747 engine

16. Poisonous Gas Emissions
Volcanic Smog-Vog
CO2, SO2, HCl, HF
H2S
Lake Nyos, Cameroon

17. Poisonous Gas Emissions Lake Nyos, Cameroon (1986)
Controlled degassing, 1995
Lake Nyos
“River” of CO2
50 m thick layer
Bottom of lake
Saturated in CO2
CO2 gas from Magma

18. Volcanic Landslides Mt. St. Helens May 18, 1980 Debris Flow
2.3 km3 of material
Largest debris landslide in recorded history

19. This downstream view of the North Fork Toutle River valley, north and west of St. Helens, shows part of the nearly 2/3 cubic miles (2.3 cubic kilometers) of debris avalanche that slid from the volcano on May 18. This is enough material to cover Washington, D.C. to a depth of 14 feet (4 meters). The avalanche traveled approximately 15 miles (24 kilometers) downstream at a velocity exceeding 150 miles per hour (240 km/hr). It left behind a hummocky deposit with an average thickness of 150 feet (45 m) and a maximum thicknes of 600 feet (180 meters).
The avalanche traveled approximately 15 miles downstream at a velocity exceeding 150 mph. It left behind a hummocky deposit with an average thickness of 150 feet and a maximum thickness of 600 feet.

20. Mt. St. Helens May 18, 1980
Figure 5.10

21. Mt. St. Helens

22. Lahars (Mudflows) A mixture of volcanic fragments and water
Mudflows are channeled along valleys on the flanks of volcanoes.
Mudflows have the consistency of wet concrete and move at high speeds (up to mph).
Pinatubo

23. Nevado del Ruiz Nov. 13, 1985
Canyon that channeled the lahar that destroyed Armero and killed 23,000 people

24. The November 13, 1985 lahar from Nevado del Ruiz
Town of Armero
The November 13, 1985 lahar from Nevado del Ruiz
The November 13, 1985 lahar from Nevado del Ruiz -- The lahar deposit forms the flat plane at the base of the River Lagunillas canyon. The lethal lahar killed over 23,000 people, most of which from from the town of Armero, located about 70 kilometers from the summit of the volcano. Courtesy of R.J. Janda, USGS.
The November 13, 1985 lahar from Nevado del Ruiz, Columbia -- After travelling over 70 kilometers from the summit of the Nevado del Ruiz volcano, this destructive lahar buried the village of Armero at the mouth of the River Lagunillas canyon, which was located in the center of this photograph. The lahar killed over 23,000 people, most of which were from Armero. Courtesy of J. Marso, USGS.

26. Volcano Monitoring and Prediction
Goal: Prevent a Volcanic Crisis from turning into a Volcanic Disaster

27. Volcanoes of the “Lower 48”

28. Volcano Monitoring and Prediction
Long-Term based on Historical Records and Geologic History
Age-dating of
volcanic deposits  Eruption Frequency
Types and amounts of
eruption products  Size of Eruption

29. Volcano Monitoring and Prediction
Short Term: systematic observations of volcano’s visible and subsurface activity
Seismicity
Ground tilt
Gas emissions

30. Rising Magma Ground Deformation
Rising magma and increasing pressure exerted by gases often cause volcanoes to deform, or swell, before an eruption

31. Rising Magma Moving Magma and Volcanic Fluids Trigger Earthquakes
High pressure causes rocks to break, triggering earthquakes
Rising magma and volcanic gases exert pressure
Magma rises into reservoir beneath volcano

32. Forecasting Volcanic Activity
Ideal Forecast includes
Location
Timing
Character of eruption and magnitude

33. Forecasting Volcanic Activity
Ideal Forecast includes
Location
Timing
Character of eruption and magnitude
Effective Forecasting involves
Scientists
Public officials
News media
Informed Public
Friday Video
Path of a Killer Volcano
Mt. Pinatubo eruption of 1991