Volcanoes

How volcanoes are formed

Two plates collide or separate
Magma rises from the mantle to the vent
This is called an eruption
Magma wells from the magma chamber and reaches the surface where it cools and hardens.
This is known as lava.
After many eruptions, layers of lava and ash build up around the vent.
As a result, a cone-shaped mountain is formed with a crater on top from which the lava flows.

Types of volcano

Active - Erupted in the past 10,000 years. (Mt. Helen's, USA)

Dormant - Has not erupted in the past 10,000 years but may erupt again. (Kilimanjaro, Tanzania)

Extinct - Never expected to erupt again. (Mount Kenya, Kenya)

Iceland - E15 (Eyjafjallajokull)

· 14 April 2010

· Very little lava

· Huge amounts of ash

· Blown south-easterly towards Europe

· 3-4 on VEI scale

Positive

· Visitor centre built, generating income for local community.

· Fertile soil

Negative

· 100,000 European flights cancelled over 8 days

· Cost airlines 145 million per day

· Loss of earnings

Positive

· Tourism

· Employment

· 2008: 500,000 visitors

· 2016: 1.8 million

Negative

· Contaminated water supply

· Evacuation of locals