Natural Hazards - Tectonic Flashcards
What are earthquakes and volcanoes caused by?
The movement of tectonic plates
Explain what the continental and oceanic crust are like
Continental - thick, less dense
Oceanic - thin, more dense
Explain the Earths structure
Crust - mantle - outer core - inner core
Explain what the inner core and outer core are like
Inner - solid ball of iron and nickel
Outer - liquid
Explain what the mantle and crust is like
Mantle - semi-molten rock which moves very slowly
Crust - very thin (about 20 km), divided into different tectonic plates
When do tectonic plates move?
When the mantle underneath them moves
What are the types of plate margin?
Destructive
Constructive
Conservative
Collision/convergent
What is a destructive plate margin?
Plates move towards each other
Oceanic and continental plates meet
The denser oceanic plate sinks
Create volcanoes, therefore crust is destroyed
What is a constructive plate margin?
2 plates move away from each other
Magma rises from the mantle, which fills the gap of where the 2 plates moved apart, the magma cools which creates new crust
What is a conservative plate margin?
2 plates move past each other, or are moving in the same direction but at different speeds
Crust isn’t created or destroyed
What is a collision/convergent plate boundary?
2 continental plates collide
Crust isn’t created or destroyed, fold mountains are created because the plates push each other up
How does a destructive plate margin create earthquakes?
If the oceanic plate gets stuck as it moves past the continental pressure builds up, then as they move past they send out vibrations which causes earthquakes
How do constructive plate margins create earthquakes?
As the plates move away from each other the pressure builds up along cracks within the plates, then as they move past each other they send out vibrations which cause the earthquake
How do conservative plate margins create earthquakes?
As the plates moving past each other get stuck and pressure builds up, then as they move past each other they send out vibrations and cause an earthquake
How does an earthquake form?
Pressure builds up as the plates move past each other
As the plates move past they send out shock waves
The shock waves spread out from the focus
What plates are volcanoes found at?
Oceanic and conservative
How do oceanic plates cause volcanoes?
The plate moves down into the mantle, where it’s melted and destroyed
A pool of magma is formed
The magma rises through the cracks in the crust
The magma erupts onto the surface, forming a volcano
How does a constructive plate cause a volcano?
Magma rises up through the gap created by the pages moving away from each other, forming a volcano
Where else do volcanoes form other than destructive/constructive plate boundaries?
Parts of the mantle that are really hot, called hotspots
What are the primary impacts of earthquakes?
Buildings and bridges collapse
People are injured or killed
Infrastructure damaged
Electricity/water/gas/telephone connections are damaged and cut off
What are the secondary impacts of earthquakes?
Can trigger landslides/tsunamis which create more damage
Homeless people due to damaged buildings
People may suffer psychological problems
Shortage of food/water more death
Unemployment due to damaged buildings
Roads are blocked because of damage meaning aid can’t get through
What makes impacts of earthquakes worse in LEDCs?
Poor quality housing, means they are more likely to be destroyed
Infrastructure is poorer, makes it harder for emergency devices to reach people leads to more death
Don’t have the money for protection/planning
Healthcare is worse more people die
Why do people continue to live where earthquakes happen?
They’ve always lived there - don’t want to leave friends/family
Don’t want to lose jobs
They don’t think an earthquake will happen again
They’re confident they will get the support from the government if an earthquake were to happen
What are the ways of reducing the impacts of earthquakes?
Prediction
Building modification
Planning
Education
Aid
How can you Predict an earthquake?
Small tremors
Cracks appearing in rocks
Strange animal behaviour
Looking at data from previous earthquakes
How can Buildings be Modified to reduce the impacts of earthquakes?
Using materials like reinforced concrete or special foundations that absorb the earthquakes energy
How can you Plan to reduce the impacts of earthquakes?
Building future buildings in areas that aren’t earthquake-prone
Firebreaks
Emergency services
Evacuation routes
What Education can be provided to reduce the impacts of earthquakes?
Tell people how to evacuate
Tell people how to make survival kits, including food, water, torch, radio, batteries ect
How can Aid help to reduce the impacts of an earthquake?
Providing food, water, money or people (doctors/rescuers) ect
What makes a way of reducing the impacts of earthquakes sustainable?
Effective, environmentally friendly, cost effective
Why do people live near to volcanoes?
Soil around the volcano is fertile, because of the minerals found in ash & lava, which attracts farmers
Volcanoes are tourist attractions
They are also a source of geothermal energy, used to create electricity, so people live nearby to work at power stations
What are the primary impacts of volcanoes?
Buildings/roads destroyed by lava and pyroclastic flows, buildings also collapse if too much ash falls on them
People/animals injured or killed by pyroclastic flows/lava/falling rocks/suffocated by CO2
Crops damaged with ash or suffocated by CO2
Water supplies contaminated with ash
What are the secondary impacts of volcanoes?
Mudflows formed by volcanic material and water, this causes more destruction death and injuries
Fires caused by lava and pyroclastic flows
People suffer from psychological problems
Shortage of food and water
Roads blocked/destroyed so aid can’t get through
Unemployment through damaged buildings
Sulphur dioxide released into the atmosphere causes acid rain
What are the ways of reducing the impacts of volcanoes?
Prediction Planning Building modification Education Aid
How can you Predict an volcano to reduce the impacts?
Small earthquakes
Escaping gas
Changes in the shape of the volcano
How can you Plan to reduce the impacts of a volcano?
Buildings built in areas that aren’t volcano-prone
Firebreaks to reduce the spread of fires
Emergency services
Evacuation routes
How can Modifying Buildings reduce the impacts of volcanoes?
Buildings can’t be built to withstand lave or pyroclastic flows
Can be strengthened so they’re less likely to crash under ash
Lava can be diverted away from buildings with barriers
How can Education reduce the impacts of volcanoes?
Evacuation routes can be made
Survival kits which contain food, water, batteries, torch, radio, and dust masks
How can aid be used to reduce the impacts of volcanoes?
Bringing in food, water, money or people
