Geography - Natural Hazards

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  • Created by: L_Georgie
  • Created on: 30-03-16 21:03
How do tectonic plates 'drift' on the Earth's surface?
The heat in the rock below the crust sets up convection movements.
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Name the layers of the Earth starting from the outside.
The crust, mantle, outer core and inner core.
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State the names of the four different types of plate boundaries.
Constructive, destructive, collision and conservative/transform.
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What happens at a constructive plate boundary?
The plates are moving apart allowing molten rocks from the mantle to come up, spread out and harden which forms a ridge of new rock.
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What tectonic hazards can occur at a constructive plate boundary and how?
Earthquakes, the movement of the plates and tension causes faults to appear. Volcanoes, molten material wells up sometimes creating volcanic islands.
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What happens at a destructive plate margin?
One plate slides beneath another as they collide. The bottom plate crumples, creating new mountains.
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What tectonic hazards can occur at a destructive plate margin and how?
Earthquakes, pressure builds between the two plates when friction stops them from moving which often ends with them suddenly jerking causing an earthquake. Volcanoes, molten rock is released as the lower plate gets pushed down which forms a volcano.
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What happens at a collision plate margin?
Two plates collide and are crushed against each other which pushes them upwards forming new mountains.
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What tectonic hazard can occur at a collision plate margin and how?
Earthquakes, as pressure builds up between the two plates.
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What happens at a conservative/transform plate margin?
Plates slide past each other (A fault line can normally be seen on the Earth's surface)
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What tectonic hazard can occur at a conservative/transform plate margin and how?
Earthquakes, the plates may become stuck and pressure builds up until the plates move with a jerk causing earthquakes.
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Where do earthquakes and volcanoes occur?
On the plate boundaries (most of the time)
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What can happen if an earthquake occurs under the sea?
They can cause massive tidal waves called a tsunami which can devastate coastal areas.
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What is the point where the earthquake starts below the Earth's surface called?
The focus or hypocentre.
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What is the point directly above the focus on the Earth's surface called?
The epicentre.
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What are the primary effects of an earthquake?
The ground shaking, buildings collapsing, cracks appearing in the ground, pipes getting broken, power supplies getting disrupted and water pipes getting broken.
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What are the secondary effects of an earthquake?
Aftershocks, landslides, tsunamis and outbreaks of disease due to disrution of water and medical supplies.
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What is the magnitude of an earthquake recorded by?
A seismometer.
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How does the Richter scale measure the power of earthquakes?
It measures the height of the shock waves and then giving it a number on a scale of 1-10 depending on power. Each point on the Richter scale is ten times more powerful than the one bellow.
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How does the Mercalli scale measure the strength of an earthquake?
It measures the earthquakes strength by it's observed effects on the buildings (1-12)
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What can effect the impact of an earthquake?
The magnitude of the quake, the density of the population, where the earthquake happens and how prepared the country is to deal with an earthquake.
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Why are the impacts of earthquakes often worse in LEDCs than MEDCs?
LEDCs may require aid to deal with the effects which takes time to arrive, lack of medical supplies and services, roads are poorly maintained, communications are poor, housing is not earthquake proof, people are not prepared and spread of disease.
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What precautions can people take against earthquakes?
Prepare an emergency pack, know where is suitable to take cover in the event of an earthquake, turn off gas water and electricity and after the earthquake move to a safe place.
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What precautions can authorities take against earthquakes?
Monitor the hazard so people can be warned, have emergency supplies ready, make plans for shelter, food and water supplies, plan to broadcast information for people effected.
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What long-term planning can be done to try and minimise the effect of earthquakes?
Ensure road and rail communications are built, ensure all new buildings are earthquake proof and educate people on what to do in the event of an earthquake.
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Why do people live in earthquake zones?
The climatic conditions may be suitable, family ties with the area, economic conditions and there may be more space available.
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Where are most volcanoes found?
On plate boundaries.
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What are the three types of volcanoes?
Composite volcano, shield volcano and dome volcano.
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What are the two types of volcanoes where they erupt explosively and violently?
Composite volcanoes and dome volcanoes.
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What type of volcano erupts gently but is still dangerous?
Shield volcanoes.
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What is the definition of an active volcano?
A volcano that has erupted recently and is likely to erupt again.
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What is the definition of a dormant volcano?
A volcano which has not erupted in a long time but it may erupt again.
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What are volcanic bombs?
Pieces of rock that are thrown into the air by a violent volcano.
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What is a pyroclastic flow?
A pyroclastic flow is a fast moving current of hot gas and rock.
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How do mud flows (lahars) form?
They form when hot ash melts snow and ice or falls into rivers often due to rainfall.
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What are the primary effects of a volcanic eruption?
Volcanic blasts, lava flows, ashfalls, pyroclastic flows and earthquakes.
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What are the secondary effects of a volcanic eruption?
Lahars, landslides, sulfur dioxide being emitted and acid rain.
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What is the impact of a volcanic eruption dependent on?
The violence of the eruption, the density of the population near the volcano, how well the eruption has been predicted and how well prepared the people that near the volcano are.
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What can scientist use to help predict when a volcano is going to erupt?
the frequency of earth tremors, the movement of the magma can be measured using gravity measurements, ground temperature and the emissions of gas (sulfur dioxide).
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How can mapping help save people's lives?
They can look where old lava and lahars were and decide which areas are most and least at risk.
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Why do people live near volcanoes?
There is often rich fertile soil perfect for farming around volcanoes, there are lots of jobs in the tourism industry, geothermal energy can be harnessed and rocks from the volcanoes are rich in minerals and can be mined.
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Where are tropical storms formed?
Tropical storms often form between the tropics of Cancer and tropics of Capricorn. They form above sea warmer than 27 degrees.
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How are tropical storms formed?
Warm, damp air spirals upwards towards the top of the hurricane, as the air rises it cools forming clouds and producing torrential rain.
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What is the calmest part of a tropical storm?
The eye of the storm.
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Why do people live in known tropical storm areas?
Because it was where they were born and have lived all their lives, good farm land, coastal ports for trade and fishing and attractive beach areas which attract tourists and creates jobs.
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What are the primary effects of a tropical storm?
The wind causes high spread damage to buildings and crops, rain causes widespread flooding and storm surges occur which also causes flooding.
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What are the secondary effects of a tropical storm?
Damage to property, widespread dislocation of roads, railways and power lines, landslides, mudslides and disruption of medical and water supplies causing disease.
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How is the intensity of tropical storms measured?
They are measured on a scale of 1-5 known as the saffir-simpson hurricane scale.
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When does a storm become a hurricane?
When their average wind speed reaches 119 kilometres per hour.
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How can people be protected from tropical storms?
Prediction, close monitoring and predicting where it's path will be, planning, plan warning systems and evacuation routes, education, teaching children how to stay safe during a tropical storm and building regulations.
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What is a drought?
A prolonged period without enough precipitation to support people or crops.
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What causes a drought?
A drought can happen due to a shift in the expected weather patterns on a global scale which causes seasonal rainfall to fail.
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What is desertification?
Desertification is when fertile land becomes more like a desert meaning that vegetation can no longer grow there.
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What are the primary effects of a drought?
There is insufficient water for people animals and crops.
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What are the secondary effects of a drought?
Livestock begin to die due to no water, grater pressure is put on available grazing and woodland, farmers crops begin to fail, rivers dry up and increased risk of wildfires.
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Why do droughts usually have less of an impact in MEDCs than LEDCs?
Because MEDCs have the resources to build water transport systems, peoples livelihoods and food supply doesn't depend on a certain amount of rainfall and MEDCs can provide sustainable responses to a drought.
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What do desalination plants do?
They turn sea water into drinking water.
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Other cards in this set

Card 2

Front

Name the layers of the Earth starting from the outside.

Back

The crust, mantle, outer core and inner core.

Card 3

Front

State the names of the four different types of plate boundaries.

Back

Preview of the front of card 3

Card 4

Front

What happens at a constructive plate boundary?

Back

Preview of the front of card 4

Card 5

Front

What tectonic hazards can occur at a constructive plate boundary and how?

Back

Preview of the front of card 5
View more cards

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