1. Volcanic Hazards!
Volcanic Hazards!

2. Volcanic Fatalities 92,000 Tambora, Indonesia 1815
36,000 Krakatau, Indonesia 1883
29,000 Mt Pelee, Martinique 1902
15,000 Mt Unzen, Japan 1792
But, volcanoes cause fewer fatalities than earthquakes, hurricanes and famine.

3. Pompeii (79AD)
On August 24, 79AD Mount Vesuvius literally blew its top, erupting tonnes of molten ash, pumice and sulfuric gas miles into the atmosphere. Pyroclastic flows flowed over the city of Pompeii and surrounding areas.

5. Lava Flows
Lava Flows
Lava flows have temperatures in excess of 200 degrees Celsius. Therefore will burn any flamable material it contacts with
Usually slow speed (a few mph – 60mph)
Thick lava flows will bury all in it’s path including infrastructure (buildings, roads, waterways etc.) and agricultural land

6. Pu’u ‘O’o and Kupaianaha
• Started eruptions in 1983
• By 2002, 189 structures destroyed and 13 km of highway covered with up to 25m of lava
Flow through 2002

7. Pyroclastic Flows Pyroclastic Flows
Fluid avalanche of rock material, hot ash and gas
Can form when eruption columns collapse
Highly destructive
Typically faster than 80km/hr and up to 700°C
Can incinerate, burn, and asphyxiate people

8. Lahars Lahars Form from: Snow/ice water mixed with debris
• Like pyroclastic flows, but with more water
Form from:
Snow/ice water mixed with debris
Pyroclastic flows mixed with river water
Rainfall on loose material (ash)

9. Landslides Landslides
Large masses of earth that fall, slide or flow rapidly triggering volcanic explosions, lahars, and tsunamis

10. Volcanic Gases Volcanic Gases
Formation of acid rain (from SO2) can cause water contamination and plant damage
Prevailing winds can blow gases thousands of kilometers away

11. Tephra
Tephra
Airborne volcanic rock, consists of wide range of rock types
Larger rocks fall closer to volcano; ash can travel thousands of kilometers

12. Earthquakes Earthquakes
Volcanic earthquakes: small; caused by eruptions and movement of magma within the volcano
Tectonic earthquakes: occur at base of volcano or deep within the crust
- larger and more destructive
• April 2, 1868 – 7.9 magnitude earthquake; most destructive in Hawaiian history

13. Ground cracks and settling
Cracks: ground cracks in the area of a new eruption as magma is forced upwards
Can be 6 ft wide and a mile long
Form within hours
Settling: occurs near end of the eruption
Subsurface magma drains away and causes ground to collapse
Cracks: ground cracks in the area of a new eruption as magma is forced upwards
Can be 6 ft wide and a mile long
Form within hours
Settling: occurs near end of the eruption
Subsurface magma drains away and causes ground to collapse

14. Tsunamis Tsunamis Giant ocean waves
Cause: earthquakes or giant landslides