1. What Causes Volcanoes? 11/9/15 9-3 pgs. 230-235 IN: What causes volcanoes?

2. Formation of Magma Solid rock may become magma when: – pressure is released, – when the temperature rises above its melting point, – or when its composition changes.

5. Nonexplosive Volcano Lava flows come from nonexplosive eruption.

6. Explosive Volcano Clouds of hot debris and gases shoot out from the volcano often at supersonic speeds.

7. Shield volcanoes  nonexplosive Cinder cone volcanoes  explosive Composite volcanoes  explosive and then nonexplosive

8. Near tectonic plate boundaries. Where do volcanoes form?

10. Divergent Boundaries - when tectonic plates separate. Rift – deep crack between plates

11. Not this Divergent, Lexi!

15. Where do volcanoes form? Convergent Boundaries - when tectonic plates collide. Subduction Zones

17. Where do volcanoes form? Hot Spots – places on the Earth’s surface that are directly above columns of rising magma, called mantle plumes. 

18. Hawaii

20. Animation

21. Predicting Volcanic Eruptions Measuring Small Quakes Measuring Slope Measuring Volcanic Gases Measuring Temperature

22. Classifying Volcanoes Extinct – will never erupt Dormant – may erupt Active – are erupting

23. OUT: Why are most volcanoes on tectonic plate boundaries? 