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