Volcanoes.ppt

1. Overview of Volcanoes
Gentle Eruption = Lava Flows
Violent Eruptions = Pyroclastic Flows

2. Types of Volcanoes
Compare the composition and size of a shield volcano
and a Composite Cone

3. Shield Volcano - Big Island of Hawaii

4. Lava Fountain
What is the viscosity
of this lava?
It’s volatile content?
What’s its chemical
composition?

5. Lava River
Is this behavior
gentle or violent?

6. Lava flow cause localized damage.

7. When this
lava cools
It forms
basalt
Two types
of flows
Aa
Pahoehoe

8. Composite Cone - Philippines

9. Anatomy of a Composite Cone

10. Composite Cones Erupt Violently

11. Composite Cones
Also Erupt Gently
What is the viscosity
of this lava?
It’s volatile content?
What’s its chemical
composition?
When this lava cools it forms
Andesite

12. Volcanic Dome - Oregon

13. Volcanic Domes Fail Suddenly

14. SOME QUESTIONS
What is the viscosity of this lava?
It’s volatile content?
What’s its chemical composition?
When this lava cools it forms
Rhyolite

15. • Lava Flows
• Volatiles
• Pyroclastic Explosions
• Lahars
• Tephra
Volcanic Hazards

16. Volcanic Hazards - Lava Flows

17. Volcanic Hazards - Volatilities - VOG

18. Volcanic Hazards - Volatilities
Carbon Dioxide Asphyxiation

19. Volcanic Hazards -
Volatilities - Laze

21. Volcanic Hazards - Pyroclastic Explosion
Nuee Ardente

22. Volcanic Hazards - Lahar

23. Lahars are caused by either:
Intense rainfall around a volcanic summit
Suddenly melting snows and glaciers

24. Volcanic Hazards -
Tephra

25. Tephra or Volcanic Ash is thickest closest to a volcanic eruption