1. Volcanoes

2. Volcanoes Vents in Earth’s crust through which molten rock will flow
Occur at convergent boundaries

3. Shield Volcanoes Large gentle slopes of lava
Found on divergent boundaries and ocean hot spots

7. Small, steep volcanoes Erupt gas-rich lava
Cinder Cones
Small, steep volcanoes
Erupt gas-rich lava

11. Composite Volcanoes Large, steep-sided volcanoes
Result from explosive eruptions of lava and ash
Found on convergent boundaries

15. Volcanoes Magma Lava Molten rock UNDER Earth’s surface
Has unique chemical compositions
Lava
Magma that erupts ONTO Earth’s surface

16. Lava flows over Earth’s surface then cools and hardens
Eruption
Lava flows over Earth’s surface then cools and hardens

17. Eruption Eruption Style Volcanic ash
Determined by amount of dissolved gases and silica content
Volcanic ash
Tiny particles of pulverized volcanic rock and glass

18. Eruption Explosive (violent) Quiet
Blows ash high into atmosphere, then settles over a large area
Quiet
Hot flowing lava

19. Viscosity Viscosity A liquid’s resistance to flow
Low viscosity=flows easily
High viscosity=flows slowly

20. Pompeii Video
Science World

21. Hazards of Volcanic Eruption
Lava Flows
Slow moving
Threaten nearby communities
Damage environment

23. Effects of Volcanic Eruption
Ash Fall
Disrupts air traffic
Affects air quality; causes breathing problems
Affects climate by blocking sun and cooling atmosphere

25. Hazards of Volcanic Eruption
Mudflows
Snow and ice melted in volcano mix with mud and ash

26. Hazards of Volcanic Eruption
Pyroclastic Flow
Fast moving avalanches of hot gas, ash and rock
Travel over 100km/hr

28. Hazards of Volcanic Eruption