Volcanoes 8

Volcanoes

What is it a volcano? A volcano is a mountain that it has magma inside it. It’s like a chimney in the Earth’s crust (surface).

Parts of a volcano The parts of a volcano are: 1)Vent 2)Hard lava 3)Magma 4)Magma chamber 2

1 3 4

What is it... -Magma is liquid rock that rises to the Earth’s surface from the mantle. -Lava is when the magma leaves the vent. -The vent is the hole of a volcano.

The plate tectonics theory The plate tectonics is a theory that explains how volcanoes form. Some volcanoes form above a hot spot. The hot spot is a very hot place in the mantle, just below a plate.

Plate movements Plates bumping

Plates moving inside

Plates moving apart

A volcanic eruption A volcanic eruption contains: gas, dust, water vapour, ash, lava and magma.

Groups of volcanoes There are three groups of volcanoes: - An active volcano is one that is erupting or will soon erupt. - A dormant volcano is one that hasn’t erupted for a long time. - An extinct volcano is one that hasn’t erupted for more than 10,000 years.

Types of tephra Tephra are fragments of igneous rocks that erupt from a vent.

Bomb

Dust

Lapilli

Pele’s Hair

Ash

aa

Pahoehoe

Underwater volcanoes In the floor of the ocean there are flat plains, mountain ridges, canyons and trenches. There are more volcanoes under the ocean than on land. Underwater volcanoes form in the same way as land volcanoes.

People live near volcanoes because: -The minerals and chemicals in the lava and ash make the soil fertile so it’s good for farming. -Volcanoes help to produce electricity. This electricity is called geothermal energy.

Volcanologists Volcanologists are scientists that study volcanoes in different ways. It’s a dangerous work but they help the people that live near volcanoes. They use special suits while they collect lava.