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 buildings.

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 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 margins which means they experience earthquakes e.g. Tokyo in Japan. 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 because they don’t have money to move.

3. Climate change is leading to more frequent and stronger tropical storms. As sea levels rise, many more areas will be at risk from coastal flooding.

4. Farming – Land next to rivers and volcanoes is good for farming so people choose to live there for that reason.

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 section of the Earth’s crust.

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)

• 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 slide 7-8.

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)

• 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 7-8 for why.

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.

Remember to give the full sequence!!!

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

Why do earthquakes occur at a constructive 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.

Remember to give the full sequence!!!

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?

The effects that happen as a direct result of the earthquake/volcano.

Refer to:

Death, injury, damage, destruction.

What are secondary effects?

Effects that happen afterwards such as disease from contaminated water or education suffering.

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?

The reaction of people as the disaster happens and straight after it (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?

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 were destroyed or damaged.

• Transport and communication links were also badly damaged

• Hospitals and schools were badly damaged.

Secondary effects:

• 1.3 million people were made homeless.

• The estimated cost of damage was $14 billion.

• Many people lost their jobs.

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

• 1 million people had to live in temporary camps.

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

Short term responses:

• People dug survivors out of the rubble with their hands.

• Tents were provided for people to live in.

• Food was supplied to those in need.

• 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.

• The government in Haiti was weak. They had to rely on other countries and aid to help them.

Long term responses:

• Aid came from many places including the USA and EU (European Union)

• After 1 year re-building of homes and services had begun but people are still left without homes even today.

• 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.

• 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.

• Cost of damage estimated $40 billion.

• Divorce rates increased.

• The population of Christchurch fell as people moved away.

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 supplies were fixed and back on quickly.

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

• Rebuilding of the area started quickly and has made good progress.

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 people live in poorly built housing. (“earthquakes don’t kill people – buildings do!)

• In contrast, New Zealand builds earthquake proof buildings and people know what to do in an earthquake so the effects were not as bad.

• 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

• The effects in Haiti were mainly social because of the high loss of human life, people’s homes etc. The economic 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.

• The Haiti government was weak and disorganised. 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.

• New Zealand rebuilt much more quickly because they had the money.

• 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 (good) 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.

• Geothermal power got from the heat underground is a cheap and clean form of energy (no greenhouse gases produced)

In poorer countries people may have no choice because they don’t have the money to leave. They may also not know about the risks if the volcano has not erupted recently.

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, People live in cities because the buildings are earthquake proof and they know what to do in an earthquake so they feel safer.

In LICs people don’t have the choice because they haven’t got enough money to move. They may not know about the danger because of a lack of education.

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 and having well trained emergency services.

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionSlide 21: Management of tectonic hazards

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.

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.

• People should be educated in what to do in a volcanic eruption.

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionSlide 22: Management of tectonic hazards

Earthquakes

Monitoring:

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

• Earthquakes can be monitored using seismometers. Often there are smaller earthquakes before a big 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.

TOPIC: The Challenge of Natural Hazards – Tectonic Hazards sectionSlide 23: Management of tectonic hazards

Earthquakes

Protection:

• Buildings should be earthquake proof and there are rules on how to build.

• 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.

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.