Volcanoes

General Volcano Info.• Most of the thousands of

volcanoes on earth are inactive.

• Earth has about 600 active volcanoes right now.

• The most active volcano on earth is Kilauea on the island of Hawaii.

Causes of Volcanoes

•1. Divergent Boundaries: Tectonic plates pull apart, lava oozes out.

•2. Convergent Boundaries: Two plates meet, the ocean plate dives under the continent plate. The melted material forms volcanoes. (Subduction)

•3. Hot Spots: Some areas of the mantle are hotter than others. Over these “hot spots” magma forces its way to the surface.

Types of Eruptions• 1. Explosive: Sometimes

called a loud eruption, these are explosive, violent eruptions.

• 2. Quiet: In a quiet eruption, lava quietly flows out of a volcano.

Types of Volcanoes• 1. Shield Volcano: A shield

volcano is formed by quiet eruptions of lava. Kilauea is a shield volcano.

• Gently sloping sides – Low Silica Lava – Not Explosive.

•2. Cinder Cone Volcano: A cinder cone volcano is an explosive volcano.

•Steep sides - High Silica Lava – Tephra (Ash & Lava) – Explosive – Lava Bombs.

•Composite or Strato Volcano: Some eruptions are quiet and some are explosive.

•Can be Lava or Tephra. – Medium steep sides – Layers of Lava & Tephra.

BrainPop

• http://www.brainpop.com/science/theearthsystem/volcanoes/zoom.weml

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