topic: the challenge of natural hazards –...

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionSlide 1: Natural hazards

Define natural hazard. (2 marks)

What is a natural hazard?

• A natural event (for example an earthquake, volcanic eruption, tropical storm, flood) that threatens people or has the potential to cause damage, destruction and death.

Types of natural hazard:

• Tectonic hazards – created by the movement of tectonic plates. E.g. earthquake

• Atmospheric hazards – occur in the atmosphere. E.g. hurricane

• Geomorphological hazards – occur on the land surface. E.g. flooding

• Biological hazards – involve living organisms. E.g. forest fires or spread of disease.

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionSlide 2: Hazard Risk

Explain two factors that influence hazard risk. (4marks)

What is hazard risk?

The probability or chance that a natural hazard may take place.

A natural event becomes a hazard when it occurs near to people.

What factors affect hazard risk?

1. Urbanisation – over 50% of the world’s population now live in cities. Many cities are near plate boundaries which means they experience earthquakes e.g. Tokyo in Japan or Istanbul in Turkey. As cities grow, more people are at risk from these hazards.

2. Poverty – In poorer parts of the world, people have no choice but to live in areas at risk. In the city of Lima in Peru, a shortage of housing has led people to build on slopes prone to landslides. In LICS there are less likely to be earthquake proof buildings which will make the population more vulnerable.

3. Climate change – In a warming world, the atmosphere has more energy which leads to more frequent and stronger tropical storms. As sea levels rise, many more areas will be at risk from coastal flooding e.g. low lying parts of Bangladesh.

4. Farming – land next to rivers tends to be fertile as it has been deposited by the river. People choose to live next to river because of the good farmland but at the same time put themselves at risk of flooding.

5. Population growth – this leads to more people living where hazards might occur.

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionSlide 3: Tectonic hazards

What is a tectonic hazard?

A natural hazard caused by movement of tectonic plates (including volcanoes and earthquakes).

What is a tectonic plate?

A rigid segment of the Earth’s crust which can ‘float’ across the heavier, semi-molten rock in the mantle below.

Plates move in different directions. Why?

Due to convection currents in the mantle below dragging them around.

What is a plate margin?

The boundary between two tectonic plates.

There are three types of plate margin that can occur, depending on the direction of movement of the plates.

See the next slide for a map of the world’s major plates.

• The Pacific plate and North American plate move alongside each other. This is a…

conservative plate margin.

• The North American plate and Eurasian plates move apart. This is a…

Constructive plate margin

• The Nazca and South American plate move towards each other – this is a…

Destructive plate margin.

Describe the distribution of earthquakes.

• Earthquakes occur in a linear pattern (in lines) following the plate margins.

• Lots of earthquakes occur down the west coast of North and South America. (destructive plate boundary)

• There is a line down the centre of the Atlantic ocean (constructive plate boundary)

• as well as many around the edge of the Pacific Ocean –this is called the ring of fire.

Explain the distribution of earthquakes.

• Most earthquakes occur at the plate boundaries – see slides

• Those that occur away from plate boundaries are caused by human activity such as mining or oil extraction.

Describe the distribution of volcanoes

• Volcanoes occur in a linear pattern (in lines) following destructive and constructive plate margins.

• Lots of volcanoes occur down the west coast of South America. (destructive plate boundary)

• There are some down the centre of the Atlantic ocean (constructive plate boundary)

• as well as many around the edge of the Pacific Ocean –this is called the ring of fire.

Explain the distribution of volcanoes.

• Most volcanoes occur at destructive and constructive plate boundaries – see slides for why.

• Those that occur away from plate boundaries form over hotspots which are areas where the mantle comes closer to the Earth’s surface than normal.

How do volcanoes form at a destructive plate boundary?

1. An oceanic and a continental plate move towards each other due to convection currents in the mantle.

2. The oceanic plate dives under the continental plate because it is denser. This is called subduction.

3. As the oceanic plate gets closer to the hot core it melts generating a lot of magma.

4. This magma rises up through cracks in the crust and may erupt at the surface as a volcano.

Why do earthquakes occur at a destructive plate boundary?

1. An oceanic and a continental plate move towards each other due to convection currents in the mantle.

2. The oceanic plate dives under the continental plate because it is denser. This is called subduction.

3. Where the two plates are scraping together, they may get stuck. Pressure will build up over time which will eventually be released as an earthquake.

Remember to give the full sequence!!!

How do volcanoes form at a constructive plate boundary?

1. Two oceanic plates move apart due to convection currents in the mantle.

2. As the plates pull away from each other, magma from the mantle rises and solidifies to plug the gap.

3. In a few places, magma erupts on the surface producing runny lava that flows along way so the volcanoes are gently sloping.

4. This type of volcano is called a shield volcano.

5. If enough eruptions occur, the volcano may emerge above the ocean surface and form a volcanic island such as Iceland.

Why do earthquakes occur at a constructive plate boundary?

1. Two oceanic plates move apart due to convection currents in the mantle.

2. As the plates pull away from each other, magma from the mantle rises and solidifies to plug the gap.

3. As the plates move, cracks sometimes form in them at right angles to the plate margin.

4. The two sides of the crack may lock together, pressure builds up and may be released as a small earthquake.


Volcanoes don’t occur at conservative plate boundaries because there is no magma near the surface.

Why do earthquakes occur at a conservative plate boundary?

1. Two plates move alongside each other either in opposite directions or the same direction at different speeds. This movement is due to convection currents in the mantle.

2. The plates may lock together, pressure builds up and will eventually be released as an earthquake.


TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionSlide 10: Effects of earthquakes

Using examples, explain why more people die in some earthquakes than others. (9marks)Describe the secondary effects of earthquakes. (4marks)For an earthquake you have studied were the primary or secondary effects more severe? (9marks)

What are primary effects?

AQA definition:

The initial impact of a natural event on people and property, caused directly by it, for instance the ground buildings collapsing following an earthquake.

Refer to:

Death, injury, damage, destruction.

What are secondary effects?

AQA definition: The after-effects that occur as indirect impacts of a natural event, sometimes on a longer timescale, for instance fires due to ruptured gas mains resulting from the ground shaking.

Other examples include death from disease due to contaminated water, Children’s education suffering because they can’t go to school. People being made homeless as a result of their houses collapsing.

Effects can also be classified as…

Economic (money and jobs), social (people – housing, healthcare, education, crime) and environmental (surroundings)

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionSlide 11: Responses to earthquakes

Describe the immediate responses to earthquakes. (4marks)Suggest why the response in some earthquakes is more effective than others. (6marks)

Responses are what people do after the event to try to cope with it.

They can be divided into immediate and long term responses.

What are immediate responses?

AQA definition: The reaction of people as the disaster happens and in the immediate aftermath.

(Think within the first month.) Some examples are…

• Pulling people out of the rubble and rescue teams with dogs coming to people’s rescue.

• Leaving buildings to escape an earthquake.

• Burying bodies and trying to help the injured.

• Setting up temporary tents and shelters. Supplying food and water to people who need it.

What are long term responses?

AQA definition: Later reactions that occur in the weeks, months and years after the event. Examples are…

Rebuilding damaged buildings and areas

Repairing infrastructure such as roads and water supplies

Putting in place education/building regulations to reduce the damage done next time.

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionSlide 12: LIC example – Haiti earthquake 2010

Haiti is an island in the Caribbean. The 2010 earthquake measured 7 on the Richter scale and occurred near the capital Port au Prince.

Primary effects:

• 250,000 people killed.

• 250,000 homes and 30,000 other buildings, including the President’s Palace and 60% of government buildings, were either destroyed or badly damaged.

• Transport and communication links were also badly damaged

• Hospitals (50+) and schools (1,300+) were badly damaged, as was the airport’s control tower

Secondary effects:

• 1.3 million people were made homeless.

• The estimated cost of damage was $14 billion.

• 1 in 5 people (20%) lost their jobs because so many buildings were destroyed. Haiti’s largest industry, clothing was one of the worst affected

• The large number of bodies left lining the streets meant that diseases, especially cholera, became a serious problem.

• 1 million people had to live in temporary camps. 600,000 people moved away from their homes and to countryside areas in Haiti.

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionSlide 1: LIC example - Haiti

Short term responses:

• Medical teams treated people in make shift hospitals organised mainly by the red cross. Many people had to try and dig out survivors with their hands.

• Over 115,000 tents had to be provided for people to live in.

• 4.3 million people provided with food rations in the weeks following the earthquake.

• Lack of immediate aid through poor planning, management and access meant that people had to try and rescue each other

• It was difficult getting aid into the area because of the damage to the airport and generally poor management of the situation. Aid was left at the airport and the port was also badly damaged.

• The government in Haiti was weak and many government buildings had been destroyed. This coupled with the fact that Haiti is extremely poor meant that Haiti has to rely on aid and security forces coming in from elsewhere such as the US to keep order.

Long term responses:

• $100 million in aid given by the USA and $330 million by the European Union. 1 million people had to live in temporary camps.

• After 1 year re-building of homes and services had begun but it is believed there are still 1,300 camps full of people without homes.

• Cash for work programs have been introduced; paying Haitian people to rebuild and clear away rubble.

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionSlide 14: HIC example – Christchurch, New Zealand, 2011

Magnitude 6.3 earthquake close to the city of Christchurch.

Primary effects:

• The earthquake killed 185 people. Half of the deaths occurred in the 6 story Canterbury Television building which collapsed and caught fire..

• Infrastructure (water pipes, roads, bridges, powerlines, phone lines) was broken or damaged.

• 80% water and sewage system damaged.

• Over 3,000 people were injured.

• 100,000 buildings were damaged.

Secondary effects:

• Many people reported financial difficulties after the earthquake.

• Many people were affected psychologically because of the frequent aftershocks.

• 10,000 buildings had to be demolished because of the damage done to foundations by liquefaction.

• Cost of damage estimated $40 billion.

• Divorce rates increased.

• The population of Christchurch fell.

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionSlide 15: HIC example – Christchurch, New Zealand, 2011

Immediate responses:

• The government declared a state of national emergency.

• People were rescued from buildings.

• People came to help from other places in New Zealand e.g. the Farmy Army made up of 800 farmers.

• Chemical toilets provided for 30,000 residents.

• Rescue crews came from all over the world to help (Japan, US, UK, Taiwan, Australia)

• The government provided temporary housing.

Long term responses:

• Aid money poured in e.g. Australia gave $5 million.

• Water and sewage was restored for all residents by August.

• Charities such as Save the Children helped with the long term recovery.

• The Earthquake Recovery Authority was created to organise rebuilding of the area.

• Christchurch was divided into zones which could and could not be built on.

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionSlide 16: Comparing Christchurch and Haiti

How and why did the effects of the two earthquakes differ?

• Haiti’s effects were much worse (more deaths, damage, buildings destroyed.) This is mainly because Haiti is an LIC and many people in Port au Prince lived in poorly built slum housing which just collapsed easily during the earthquake (“earthquakes don’t kill people – buildings do!)

• In contrast, New Zealand are experienced at dealing with earthquakes and have strict building codes and regulations in place. Few buildings collapsed in the earthquake. (half of those killed were in one building) People are educated and experienced at what to do in an earthquake therefore the effects were much less.

• Christchurch had had an earthquake 6 months earlier. Haiti hadn’t had one almost in living memory so people did not know what to do.

• The effects were lessened by the effective response in New Zealand. In Haiti, the response was ineffective which made the effects worse.

• The effects in Christchurch were mainly economic because of the high cost of rebuilding (many buildings had been damaged by liquefaction even though they didn’t fall down.)

• The effects in Haiti were mainly social because of the high loss of human life, people’s homes etc. The cost of the earthquake was much lower because of the poor quality of the buildings that were there.

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionSlide 17: Comparing Christchurch and Haiti

How and why did the responses to the two earthquakes differ?

• The New Zealand government responded quickly and effectively, declaring a state of emergency. They were backed up soon after by aid from Australia and others as well as Charities such as the Red Cross. Emergency water and toilets were quickly set up as well as housing for those who needed it.

• The Haiti government was weak, disorganised as were the police and Haiti has to rely completely on an outside response from the USA, UN and others for relief, aid and security. It was ineffective also because the port and airport as well as road and communications systems had been badly damaged and it was very difficult to get aid to where it was needed. The response was incredibly slow which led to worse effects.

• New Zealand infrastructure was better which enabled them to respond more effectively. Haiti infrastructure was largely wiped out.

• The New Zealand rebuild was quite slow for an HIC, mainly because of the disruption of many large earthquakes for months after the main one.

• The Haiti rebuild however, has been much slower because of the lack of resources in the country and many people still haven’t returned home or recovered. The long term recovery has also been hindered by other natural hazards such as hurricane Matthew in 2017.

• People in New Zealand often had insurance to cover the costs incurred by the earthquake. Haitians had to start from scratch.

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionSlide: Reasons why people continue to live in areas at risk from tectonic hazards:

Explain why people continue to live in places at risk from volcanoes and earthquakes. (4marks)

There are many benefits of living near volcanoes:

• Volcanoes are surrounded by fertile land because of the minerals added to the soil through ash. This means they are great places to grow food.

• Tourists go to visit volcanic areas. This means there are jobs available in the tourist industry and money to be made. An example of a volcanic area that attracts tourists is the Blue Lagoon in Iceland – lakes heated by magma underground that tourists can swim in.

• Geothermal power can be obtained by pumping water down into the ground to be heated by magma. The resulting steam then turns a turbine and electricity is created. This is a cheap and clean form of energy (no greenhouse gases produced)

In addition, in poorer countries, settlements may have grown at the foot of a volcano because of the fertile land and that now people live there they don’t have the money or resources to leave. They may also feel that the benefits of living near avolcano outweigh the risks, especially if the volcano has been dormant (asleep) for a long time.

Many big cities are built near plate margins where there is a risk of earthquakes.

In HICS, Tokyo and San Francisco are examples where people take the risk because of the opportunities for them in the city. These cities are designed with earthquake proof buildings and people are educated about what to do in an earthquake which makes them feel safer.

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionSlide:

Why do people live where there are earthquakes?

Many big cities are built near plate margins where there is a risk of earthquakes.

In HICS, Tokyo and San Francisco are examples where people take the risk because of the opportunities for them in the city. These cities are designed with earthquake proof buildings and people are educated about what to do in an earthquake which makes them feel safer.

In LICs however, cities are not safe in an earthquake because of the lack of funds to build earthquake proof homes. E.g. Port au Prince in Haiti.

People live in these places through lack of choice. They may have moved to the city because of problems in the countryside and therefore have no choice but to try their luck. They also may not be educated about earthquakes so are unaware of the dangers.

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionSlide 20: Management of tectonic hazards

Outline one way in which volcanoes can be monitored.Explain how planning can reduce the effects of an earthquake. (4marks)To what extent can protection and planning reduce the effects of tectonic hazards. (9marks)

Monitoring, prediction, protection, planning

Key definitions:

• Monitoring:

Using scientific equipment detect warning signs of an earthquake or volcanic eruption.

• Prediction:

Attempts to forecast when and where a natural hazard will strike, based on current knowledge.

• Protection: THINK BUILDINGS!!

Actions taken before a hazard strikes to reduce its impact, such as educating people or improving building design.

• Planning:

Actions taken to enable communities to respond to, and recover from, natural disasters, through measures such as emergency evacuation plans, information management, communications and warning systems.


Volcanoes:

Monitoring:

• As magma rises, gases such as sulphur dioxide may escape. This can be measured.

• Earthquakes can be monitored using seismometers. Earthquakes can be triggered by the movement of magma underground.

• As magma rises, the ground may swell. This ground deformation can be monitored using satellites.

Prediction:

• Predicting these is often possible with careful monitoring techniques.

Protection:

• It is impossible to build buildings to withstand lava flows, lahars or pyroclastic flows. On a couple of occasions in the past, lava flows have been slowed or diverted by pumping cold water onto them.

Planning:

• Emergency services should be well trained and well equipped to deal with a disaster.

• Hazard maps are produced for the areas around volcanoes showing the places that may be affected. These can be used to plan land use or evacuation routes.


Earthquakes

Monitoring:

• As plates shift, the ground moves. This can be monitored using satellites.

• Earthquakes can be monitored using seismometers. Often there are a series of foreshocks before the main one.

Prediction:

• Predicting these is extremely difficult.

• Animals often detect earth movements before humans so changes in animal behaviour can be a sign something is about to happen.


Earthquakes

Protection:

• Strict planning and building regulations need to be in place to ensure buildings can withstand this type of hazard. Buildings should be earthquake proof.

• People should be educated in what to do in the event of a disaster in order to keep themselves safe and avoid panic. (This also comes under planning.)

• Regular earthquake drills keep people prepared. (Also under planning)

• Tsunami walls can be built at the coast to hold back tsunami waves to protect towns and important buildings such as a nuclear power station.

Planning:

• Emergency services should be well trained and well equipped to deal with a disaster.

• Maps can be produced to show the likely effects of an earthquake. This helps to ensure important locations (e.g. hospitals, reservoirs and office blocks are protected.

New Zealand is an example of a country that has the money and experience to do all these things well.

Haiti is an example of a country that doesn’t do these things because of lack of money, organisation and a weak government.

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionQuiz:

Name a city near to a plate margin.

Tokyo, Istanbul

What % of the global population lives in urban areas?

50

Name a city where people have built on steep slopes

Lima, Peru

Name a country at risk from rising sea levels

Maldives, Bangladesh

At which plate boundary do the plates move a) apart, B) side by side and c) towards each other?

a) Constructive b) conservative c) destructive

In what year was a) the Haiti earthquake and b) the Christchurch earthquake?

a) 2010 b) 2011

What was the magnitude on the Richer Scale of a) the Haiti earthquake and b) the Christchurch earthquake

a) 7 b) 6.3

b) What is the name of the capital of Haiti?

c) Port au Prince

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionQuiz:

How many people died in a) Haiti and b) Christchurch

a) 250,000 b) 185

How many buildings were damaged and destroyed in a) Haiti and b) Christchurch

a) 280,000 (damaged or destroyed) b) 100,000 (damaged)

What was the cost of the damage in a) Haiti and b) Christchurch

a) $14 billion b)$40 billion

Name a volcanic area that attracts tourists.

The Blue Lagoon in Iceland.

topic: the challenge of natural hazards –...

Documents