Introduction to Volcanoes!8SCIENCE

ECUADOR

PASTO

INDONESIA

MEXICO

COSTA RICA

What is a volcano?• A volcano is an opening in the Earth’s surface• Most volcanoes are dormant – Not currently active

• Active volcanoes– Hawaii: Kilauea volcano– Iceland: “the land of fire and ice”

How is a volcano formed?• Inside the earth heat

and pressure causes rock to melt and turn to magma

• Magma is forced up to the surface of the Earth because it is less dense – flows out through an

opening called a vent

• The lava cools quickly to form layers

Where do volcanoes occur?• Directly related to the

movement of the Earth’s plates along plate boundaries

• Occur where tectonic plates are moving together or apart

• Or may be formed by a hot spot

• Plates moving apart: Mid-Atlantic ridge separates and forms long cracks

• Plates moving together: Nazca and South American plates are being forced under the Caribbean plates

Hot Spots• Hot spots: Ex. Hawaiian islands are

volcanic islands but are not found on the edge of the plates

• Some areas in the mantle are hotter than others• These hot spots melt rock and it is forced upwards

towards the crust • Volcanoes are formed in a line because the Pacific

plate is moving over the hot spot