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.

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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