Volcanoes 4

A volcano is like a chimney in the Earth’s crust (surface) where magma flows out. Magma: Solid rocks melts to form hot liquid rock called magma.

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

Magma chamber Outer core magma

mantle

Inner core

vent

Hard lava

Contents: gas, dust, water vapor, lava and ash. Scientists put volcanoes into three groups: -An active volcano: is one that is erupting or will soon erupt. -A dormant volcano: is one that has not erupted for a long time. -An extinct volcano: is one that has not erupted more than 10.000 years.

Types of a volcano: -fissure volcano -shield volcano – dome volcano – ash-cinder volcano –composite volcano –caldera volcano.

Volcanoes produce lava and rocks we find on the Earth’s Surface. Magma forms igneous rocks. These are called thepra. TYPES OF TEPHRA: bomb,lapilli,ash,dust. -Liquid lava forms igneous rocks : AA, Pahoehoe, Pele’s Hair.

PAHOEHOE

Pele’s Hair

AA

The floor of the ocean is similar to dry land. There are flat plains, mountains ridges, canyons and trenches in the ocean floor. There are more volcanoes under the oceans than on land.

The minerals and chemicals in the lava and ash make soil fertile so it’s good for farming. Volcanoes help to produce electricity. They heat rocks that are near the Earth’s crust When these rocks heat underwater , it turns to stem. People use this steam to make electricity. This is called geothermal energy.

Special scientists are called volcanologists. They study volcanoes in different ways. They study rocks and ash from a long time ago. This helps to learn about the volcano’s history and to know wat it is going to do. Because of this, people who live near volcanoes can plan what to do. Volcanologists wear special suits while they collect lava.

This is a volcanologist

This is a volcanic eruption.

• Jean-Marc Sedó • Carles Riba