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Geography❌ > Tectonic hazards > Flashcards

Tectonic hazards Flashcards

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1
Q

What is a natural hazard?

A

It’s a natural process which could cause death, injury or disruption to humans, or destroy property and possessions.

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2
Q

What is a natural disaster?

A

It’s a natural hazard that has actually happened.

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3
Q

Name the two main types of natural hazards

A
  1. Geological hazards

2. Meteorological hazards

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4
Q

What is a geological hazard?

A

Caused by land and tectonic processes.

Examples include - volcanoes, earthquakes, landslides and avalanches

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5
Q

What is a meteorological hazard?

A

They’re caused by weather and climate.

Examples include - tropical storms and other extreme weather (heatwaves, cold spells and climate change).

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6
Q

What is a hazard risk?

A

It’s the probability that a natural hazard occurs.

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7
Q

Name the different factors that affect the hazard risk

A
  1. Vulnerability
  2. Capacity to cope
  3. Nature of natural hazards
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8
Q

What is vulnerability?

A

The more people that are in areas exposed to natural hazards, the greater the probability they will be affected by a natural hazard = hazard risk is greater.
For example an area with high population density on a flood plain (Bangladesh) is very vulnerable to flooding caused by extreme weather.

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9
Q

What does the capacity to cope mean?

A

Natural hazards have to affect human activity to count as a hazard. The better a population can cope with an extreme event, the lover the threat.

For example higher income countries are better able to cope with flooding because they can afford flood defences and to repair damage afterwards.

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10
Q

What does nature of natural hazards mean?

A

Type - the hazard risk from some hazards is greater than others.
E.g - tropical storms can be monitored and predicted but earthquakes happen very suddenly with no warning.

Frequency - some natural hazards occur more often than others, increasing the hazard risk.

Magnitude - more severe natural hazards cause greater affects than less severe natural hazards.

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11
Q

Name the four parts of the earth

A
  1. The inner core - solid ball of iron and nickel.
  2. The outer core - liquid iron and nickel.
  3. The mantle - semi-molten rock that moves very slowly.
  4. The crust - divided into slabs called tectonic plates.
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12
Q

Name the two types of crust

A
  1. Continental - thicker (30-50km) and less dense.

2. Oceanic - thinner (5-10km) and more dense.

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13
Q

Why do the plates move?

A

Because of convection currents in the mantle underneath the crust.

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14
Q

Name the types of plate margins

A
  1. Destructive
  2. Constructive
  3. Conservative
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15
Q

What are destructive plate margins?

A
  • where two plates are moving towards each other
    1. where an oceanic plate meets a continental plate, the denser oceanic plate is forced down into the mantle and destroyed. This often causes volcanoes and ocean trenches.
    2. where to continental plates meet, they collide and the ground is folded and forced upwards to create mountain ranges.
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16
Q

What are constructive plate margins?

A
  • where two plates are moving away from each other

- magma (molten rock) rises from the mantle to fill the gap and cools, creating new crust.

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17
Q

What are conservative plate margins?

A
  • where two plates are moving sideways past each other or are moving in the same direction but at different speeds.
  • crust isn’t created or destroyed.
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18
Q

What plate margins are volcanoes found at?

A

Destructive and constructive.

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19
Q

How are volcanoes formed at destructive plate margins?

A
  1. The oceanic plate moves down into the mantle, where its melted and destroyed.
  2. A pool of magma forms
  3. The magma rises through cracks in the crust called vents.
  4. The magma erupts onto the surface (where its called lava) forming a volcano.
20
Q

How are volcanoes formed at constructive margins?

A
  1. Magma rises up into the gap created by the plates moving apart, forming a volcano.
21
Q

What do volcanoes emit?

A
  1. Lava
  2. Gases
  3. Ash - cover land and block the sun and form pyroclastic flows
22
Q

What’s a pyroclastic flow?

A

A super-heated current of gas, ash and rock

23
Q

Where do earthquakes occur?

A

At all three plate margins

  1. Destructive - tension builds up when one plate gets stuck as it’s moving down past the other into the mantle.
  2. Constructive - tension builds along cracks within the plates as they move away from each other.
  3. Conservative - tension builds up when plates that are grinding past each other get stuck
24
Q

How do earthquakes form?

A
  1. They’re caused by the tension that builds up at the plate margins.
  2. The plates eventually jerk past each other, sending out shock waves (vibrations). These vibrations are the earthquakes.
  3. The shock waves spread out from the focus.
25
Q

What is the focus?

A

It’s the point in the earth where the earthquakes starts.

Near the focus the waves are stronger and cause more damage.

26
Q

What is the epicentre?

A

It’s the point on the earths surface straight above the focus.

27
Q

How are earthquakes measure?

A

Using the moment magnitude scale.

28
Q

How does the moment magnitude scale work?

A
  1. Measures the amount of energy released by an earthquake

2. It’s logarithmic - magnitude 7 is ten times more powerful than a magnitude 6 earthquake.

29
Q

Ratings of earthquakes

A

Magnitude 6 and below - normally only cause slight damage to buildings, although they can be worse in very built up areas.

Magnitude 7 and above - can cause major damage and deaths.

30
Q

Name the two types of effects

A
  1. Primary - the immediate impacts

2. Secondary - what happens later on as a result of the primary effects

31
Q

Primary effects of earthquakes

A
  1. Buildings and bridges collapse, homes are destroyed
  2. People are injured and killed by collapsed buildings and falling debris.
  3. Roads, railways, ports and airports are damaged.
  4. Electricity cables, gas and water pipes and communications networks are damaged, cutting of supplies.
32
Q

Secondary effects of earthquakes

A
  1. Trigger landslides or tsunamis which destroy more buildings and cause more injuries and deaths.
  2. Leaking gas can be ignited starting fires
  3. People are left homeless and could die
  4. Shortage of clean water and a lack of sanitation makes it easier for disease to spread.
  5. Blocked roads stop aid and emergency efforts.
  6. Businesses are damaged or destroyed causing unemployment and lost income.
  7. Repairs and reconstruction can be very expensive so can weaken a country’s economy.
33
Q

Name the two types of responses

A

Immediate

Long-term

34
Q

Immediate responses of earthquakes

A
  1. Rescue people trapped by collapsed buildings and treat injured people.
  2. Recover dead bodies to prevent spread of disease.
  3. Put out fires.
  4. Set up temporary shelters for people who’s homes have been damaged/ destroyed.
  5. Provide temporary supplies of water, food, electricity, gas and communications systems.
  6. Foreign government/ charities may send aid.
35
Q

Long-term responses of earthquakes

A
  1. Re-house people who lost their homes.
  2. Repair/ rebuild damaged buildings, roads, railways and bridges.
  3. Reconnect broken electricity, water, gas and communications connections.
  4. If necessary, improve building regulations so that buildings are more resistant to damage from earthquakes.
  5. set up initiatives to help economic recovery. E.g - by promoting tourism.
36
Q

Primary effects of volcanoes

A
  1. Buildings/ roads are destroyed by lava and pyroclastic flows.
  2. People/ animals are injured/ damaged by lava, pyroclastic flows and falling rock.
  3. Crops are damaged and water is contaminated
  4. People, animals and plants are suffocated by volcanic gases.
37
Q

Secondary effects of volcanoes

A
  1. Mudflows and landslides cause more destruction, death and injury.
  2. Flooding can be caused by hot rock, gas and ashes melting the snow/ ice on the volcano and rivers and dams can get blocked.
  3. Transport networks are blocked so aid cant get through.
  4. People are left homeless and unemployed due to damaged buildings.
  5. Tourism can be disrupted.
  6. It can take a long time to recover and cost a lot.
  7. Ash can make the soil more fertile once it’s broken down.
38
Q

Immediate responses of volcanoes

A
  1. Evacuate people as soon as possible.
  2. Provide food, water and shelter.
  3. Treat injured people.
  4. Rescue people trapped/ cut off.
  5. Foreign governments/ charities may send aid.
39
Q

Long-term responses of volcanoes

A
  1. Repair and rebuild or resettle affected people somewhere else.
  2. Repair and reconnect infrastructure (roads, railways, power lines)
  3. Improve, repair and update monitoring and evacuation plans.
  4. Boost the economy if possible. E.g - by attracting tourists.
40
Q

Why do people chose to live in areas at risk from tectonic hazards?

A
  1. They’ve always lived there - friends/ family
  2. They’re employed in the area.
  3. Some people think a major eruption/ earthquake won’t happen again.
  4. Confident about government support.
  5. The soil is fertile around volcanoes - farmers.
  6. Volcanoes are tourist attractions- money.
41
Q

What do management strategies help reduce?

A

The number of deaths, injuries, homelessness and unemployment

42
Q

Name the management strategies that can reduce the effects of tectonic hazards?

A
  1. Monitoring
  2. Prediction
  3. Protection
  4. Planning
43
Q

What does monitoring mean?

A
  1. Networks of seismometers and lasers monitor the earths movements and can be used in early warning systems to give a small but vital amount of warning before a large earthquake occurs.
  2. Scientists can monitor the signs that come before a volcanic eruption
    E.g - tiny earthquakes, escaping gas and changes in the shape of the volcano.
44
Q

What does prediction mean?

A
  1. Earthquakes can’t be reliably predicted but by monitoring the movement of tectonic pats scientists can forecast which areas should be prepared.
  2. Volcanic eruptions can be predicted if the volcano is well-monitored.
45
Q

What does protection mean?

A
  1. Buildings can be designed to withstand earthquakes. E.g - reinforced concrete.
  2. Existing structures can be strengthened.
  3. Automatic shut off switches can be installed to turn off gas and and electricity supplies to prevent fires if an earthquake is detected.
46
Q

What does planning mean?

A
  1. Future developments can be planned to avoid the areas most at risk.
  2. Emergency services can train and prepare fro disasters.
  3. People can be educated so they know what to do.
  4. Governments can plan evacuation routes to get people out as quickly as possible.
  5. Emergency supplies can be stockpiled.

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