1. Earthquakes and Volcanoes

2. Magma
Magma is LESS DENSE than the rock around it and slowly forced up as lava.
(Magma Chamber – space deep in the Earth that contains the molten rock.)
What causes volcanoes?

3. Anatomy of a Volcano
Magma reaches the surface and flows out through an opening called a vent.
Lava flows out quickly and becomes solid, forming layers of igneous rock around the vent. A crater (opening at the top of a volcano) forms.
(Caldera – larger crater up to 50 km in diameter)

4. Where do volcanoes occur?
At Divergent plate Boundaries (15%)
Separated plates form long deep cracks called rifts. Lava flows out and is instantly cooled by seawater.
Ex. Iceland
Laki

8. 4/15/2010
Lightning in the ash plume of Iceland's Eyjafjallajokull volcano. Credit: Olivier Vandeginste

9. the Northern Lights have been rippling across the Icelandic sky over Eyjafjallajokull

10. At Convergent plate Boundaries (80%) – Magma is created in the subduction zone and is forced upward when 2 plates converge.

11. At hot spots (far away from plate boundaries)
– some areas in the mantle are hotter than others and melt rock, which is forced up as magma.
Ex.
Hawaiian
Islands

12. Yellowstone