Tectonics Effects and
Case Studies

Causes of volcanoes

Volcanoes can be created on constructive and destructive plate boundaries or hot spots.

At destructive plate boundaries where two plates collide and the denser plate sinks and melts. Gas and magma is released which will cool as it rises to form a volcano.

An example of a destructive plate margin is the Nazca and South American plate.

At constructive plate boundaries where two plates move away from each other the gap allows magma to be release and so this material can build up and create a volcano

An example of a constructive plate boundary is the Mid - Atlantic ridge where the North American and Eurasian plate meet.

Types of volcanoes

Shield volcano

Composite/strato volcanoes

Non-viscous lava. This means the lava is quite runny and less explosive as the air is released because it has more iron and less silica.

Shield volcanoes are normally found at constructive plate boundaries.

Shield volcanoes are non explosive because of the type of lava that they have which it thinner and less sticky.

In a shield volcano the lava travels much further. Around 180 km

The shape of a shield volcano is quite gentle and it is much fatter.

Viscous lava. This type of lava has more silica and is means the lava it much thicker and stickier. this means the lava is also more explosive because it can't leave unless it explodes

Composite volcanoes are mainly found on destructive plate boundaries.

Composite volcanoes are very explose due to the viscous lava which is thicker and stickier

The lava in a composite volcano does not travel as far. It only travels around 18 km

A composite volcano has much steeper sides and is generally thinner than a shield volcano.

Primary and Secondary effects of Volcanoes

Primary effects

People are injured and killed

Lahars

Landslides

Volcanic gases released

Lava flows

Tephra

Pyroclastic flows

Secondary effects

People are left homeless.

Lack of sanitation

Tourists can be put off

Business is reduced.

Roads, railways and airports are damged

Weakens economy

Immediate and Long term responses to volcanoes.

Immediate

Money given by other countries

Search for survivors

People sheltered

Tents given out

Free calls

Long term

Recovery money

Procession in remembrance

Free transport for some people

Rivers cleaned

Case study of Eyjafjallajökull (14 April 2010)

Effects

Primary effects

Families evacuated

Ash cloud

Glacier melting

Flash floods

Secondary effects

Farm animals moved

CO2 released

Planes can't fly. 95000 flights cancelled. Cost by June was $2 billion

Less tourists 30% less

Cooling effect due to the ash cloud

Ash in the air

Responses

Immediate

People stuck in Iceland

The south evacuation

Levees built

Air space closed

Long term

Lots more tourists visit

Nepal Earthquake (25 April 2015)

Effects

Primary effects

9,000 deaths

22,000 injured

750,000 houses damaged

Secondary effects

Avalanche on Mount Everest killed 20

Harvest lost, 50% of GDP lost

Landslides killed 250

Responses

Immediate

Long term

New taskforce to help deal with future earthquakes

$1 billion provided by India and China

Over 100 search and rescue responders sent from UK

Charities such as Red Cross came to help

Education about earthquake drills

UK provided 20 tonnes of humanitarian aid

Dams built