Natural Hazards- Earthquakes/volcanoes Flashcards Preview

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Flashcards in Natural Hazards- Earthquakes/volcanoes Deck (25):

How are convection currents created

By heat and pressure within the mantle causing the plates to move


What occurs at constructive boundaries and how does this happen?

Only volcanoes form here and this is when the plates move away from eachother leading to magma rising up the mantle and erupting. When this magma cools it forms surface of igneous rock and this is repeated until a volcano forms.


Where are constructive boundaries found?

Under the sea


What happens at destructive boundaries

Mainly volcanoes as the plates move together leading to the dense oceanic crust going under the continental crust at the subduction zone. The oceanic plate then melts to form magma which rises up cracks in continental crust and erupts at surface


At conservative boundaries only...

Earthquakes as the 2 plates stick and when pressure builds there is a sudden release of friction resulting in seismic waves being released


Give 3 reasons why people live near plate edges

Become settled before risks known
Ignore the danger
Well prepared for disasters


How do the usa protect against earthquakes

Earthquake drills
Seismometers monitor path of earthquake
Fireproof materials


How do India protect against earthquakes

As they are an LEDc they use houses built on concrete slabs in order to keep them grounded when the earthquake strikes.


Give three uses of volcanoes

Produce fertile soils for farmers as they are Rich in minerals
Provide tourism as many people want to see a dormant volcano or a thrill at seeing an active one
Provide health spas due to the naturally hot water e.g bath 49*


What is the medc example of an earthquake and what were the effects?

Japan March 2011


Magnitude 9
16,000 dead
6,000 injured
Dam collapsed
3 nuclear reactors exploded
4 million no electricity


All ports closed
Radio active gas leaks


What is an LEDc example of an earthquake and what were the effects?

Yogyakarta Java may 2006


6,000 dead
37,000 injured
Led to volcanic eruption of merapi
Hindu temple damaged


1.5 million homeless
Loss of income from tourism


What is the medc example of an volcano and the effects?

Eyjaffalokull March 2010


Volcanic ash released
Six day travel ban
0.15 million tonnes of co2 released daily


800 evacuated
Shortage of importation
Air travel disruption


What is the LEDc example of a volcano and how does it affect the people?

Tungrahua Ecuador 2006


Lava destroyed 7 villages
Hundreds killed by falling rocks
Lava covered fertile land
Livestock dead


5,000 homeless
Local airport shut


Give three reasons why more people die in ledcs than in medcs

Buildings not proof against dangers
Corrupt politicians invest money into other areas
Emergency services are not as well prepared or funded to deal with them


How does prediction help reduce effect s of earthquakes

By studying plate tectonics you learn the most at risk areas and so can invest more money there into prevention


How does preparation reduce the effects of earthquakes

Earthquake drills educate the local public on how to deal with an earthquake


How does planning reduce the affect of an earthquake

Earthquake shaking maps show areas that need aid.


Give three ways to reduce the affect of a volcano

Prediction- use seismometers
Planning- first aid kits and evacuation
Preparation- filter systems and glass roofs to shed ash from them.


What is the point where pressure from an earthquake is released



The point directly above the focus is the

Epicentre and this is where most damage is felt


Give three factors affecting the impact of an earthquake

Distance from epicentre
Medc or LEDc
Population density


Define magma chamber and crater

Magma chamber- stores magma below volcano
Crater- forms at top after eruption


Where are shield volcanoes found and what do they look like?

They are found at constructive boundaries and have low sloping sides and are formed by frequent gentle eruptions of lava


Where are composite volcanoes found and what do they look like?

Found at destructive boundaries and made of pyroclastic flow of lava at 400* above


Describe some features of an earthquake proof building

Pointed roof to centre gravity to prevent swaying
Shock absorbers to absorb impact
Cross bracing to withstand pressure
Fire proof materials