Volcanoes 6

-Eruption! -The life of a volcano - Volcano landforms - Underwater volcanoes -Living with volcanoes - Volcano words -

In 1883,in Indonesia, a volcano called Kracatoa erupted at first.

The inside of the Earth is very hot. Magma is liquid rock that rises to the Earth’s surface from the mantle. A volcano is like a chimney in the Earth’s crust (surface) where magma flows out. The hole of the volcano, is called vent. When magma leaves the vent, it becomes lava

Plate tectonics explain how volcanoes form. Some volcanoes form above a hot spot, which is a very hot place in the mantle.

A volcanic eruption contains: gas, dust, water vapor, lava and ash. Scientists put volcanoes into three groups: - An Active volcano is one that erupting or will some erupt. - A Dormant volcano is one that has not erupted for long time. - An Extinct volcano is one that has not erupted for more than 10.000 years.

gas

dust

There are six types of volcanoes: -Fissure volcano - Shield volcano - Dome volcano - Ash-cinder volcano - Composite volcano - Caldera volcano

Volcanoes produce lava and rocks. Magma forms igneous rocks. Fragments of igneous rocks sometimes erupt from a vent. These fragments are called tephra. TYPES OF TEPHRA : - Bomb, lapilli, ash and dust Pahoehoe is when liquid lava flows fast and forms smooth folds that look like rope. Aa is when sticky lava gets hard. And Pele’s Hair is when sometimes lava forms long thin strings like human hair. They can be almost 2 m long.

There are volcanoes under the ocean. They form in the same way as land volcanoes. In the ocean floor there are ridges, volcanic islands, trenches, underwater volcanoes and canyons.

The minerals and chemicals in the lava and ash make the soil fertile so it is good for farming. For example, farmers plant rice in the fertile soil below Mount Merapi, and active volcano on Java. Volcanoes also help to produce electricity. They heat rocks that are near the Earth’s crust. People use this steam to make electricity. This is called geothermal energy.

Chemicals

Miners

Volcanologists study volcanoes in different ways. They also study they changes in and arround a volcano. They use special instruments , called seisometers. Volcanologists wear special suits while they collect lava.

Laia Rusiñol i Núria Pujadas

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