VolcanoesVolcanoesNot just one type Not just one type

• What are volcanoes?

• Where do they form?

• How do they erupt?

• What are the different types of volcanoes

Volcanoes are often cone-shaped, but they can take other shapes too.

The melted rock that spills out of the crater on the top of the volcano is called lava. The lava destroys everything in its path because it is very, very hot!

A volcano erupts when magma and gases find a way to escape, so they burst to the surface through a vent. An eruption can be quite gentle or very violent.

Why does a volcano erupt?

Map 1. The world patterns of volcanoes and earthquakes

South America

North America

Asia

Australasia

Europe

Africa

Where do volcanoes Where do volcanoes happen?happen?

Most volcanoes are formed on land, but there are some volcanoes that are on the ocean floor. Some of these

volcanoes emerge from the water because they are very high.

Did you know?Did you know?

Pumice stone, which comes from volcanoes, is very light because it contains lot of tiny bubbles. If there are enough bubbles, then pumice stone can float on water!

Mount Kilauea, in Hawaii, is the most active volcano on Earth because it has been erupting since 1983!

The word, ‘volcano’ comes from the name Vulcan, who was the Roman god of fire.

• • How many? How many? 1511 volcanoes in last 10,000 years

• • The biggest? The biggest? > 80,000 km3, Mauna Loa (Hawaii)

• • The highest? The highest? 6,887 m, Ojos del Salado (Chile)

• • The biggest eruption?The biggest eruption? 2,500 km3, Yellowstone, 2.2 Ma (USA)

• • First volcanologist? First volcanologist? 79 AD - Pliny the Younger

• • Total deaths? Total deaths? 238,000 (1600-1982)

Volcano facts

Types of volcanoTypes of volcano

Volcanoes can be active, dormant or extinct.

• A volcano is active, or alive, when it erupts often.• When a volcano is dormant, or sleeping, it has not erupted for a long time – but it might in the future.• A volcano is extinct, or dead, when it hasn’t erupted for at least 100,000 years.

GLOSSARYGLOSSARYBomb – a lump of rock thrown out in an eruptionCrater – a deep hollow at the top of a volcanoCrust – The top layer of the EarthEruption – the release of gases, magma and rock from a volcanoLava – melted rock that flows down the volcanoMagma – melted rock inside the EarthMolten – melted, liquidVent – a crack on the side of a volcano where magma can

escape

•Layers of ash and lava•Secondary cone•Volcanic cone•Crater•Lava flow•Magma•Main vent •Magma chamber •Volcanic bombs, ash and gases

Are all volcanoes the Are all volcanoes the same?same?

Compare the two volcanoes

(compare means say what the differences/similarities

are)

Eruption patternsEruption patterns

There are three different levels of eruption:

1. If it easy for the gases to escape, then the eruption is very gentle. However, the lava is very runny and can move very fast.

2. Gas builds up and lumps of rock (‘bombs’) and ash burst out of the volcano. This makes the lava thick and sticky.

3. This is the fiercest eruption of all because the gases and magma become trapped inside the volcano. This causes a huge explosion, which can be big enough to remove the top of the whole mountain!

Composite Cone

The volcano is built up of alternate layers of LAVA and ASH. They can explode with great violence.

Mt St Helens - USA

Conelet

Dyke

Crater

Ash layer

Lava Layer Flank eruption

LavaFlow

Crust

Pyroclastic Flow

Shield ( Basic) Cone

Shield Volcanoes are enormous featuresbuilt up only from layers of lava. They produce lots of lava but they tend not to erupt violently.

Mauna Loa Hawaii -USA

250 miles

10,000m

Composite volcano to scale

Layers of Lava Lava Flow

Ash and Cinder ConeParacutin - Mexico

Layers of Ash and Cinder

Volcanic Bombs

Pipe

The volcano is built up of layers of ASH. When it erupts it is normally with great explosive force.

3,000m