Natural Hazards

Case studies used in this are: L'Aquila, Nepal, Typhoon Haiyan, and Somerset Level floods

What is a natural hazard?

Events that are naturally occurring and non-preventative with a negative effect on life.

What is a risk?

Probability of a hazard occurring

What is a hazard perception?

The way that people view the risk caused by the hazard

What is hazard impact?

The actual impact of the hazard

Tectonic hazards

Earthquake, volcanic eruption, tsunami

Geomorphological hazards

Avalanche, landslide

Biological hazard

Locust swarm, forest fire

Atmospheric hazard

Floods, heatwaves, drought

Low risk factors

• Good education

• Money available

• high quality infrastructure

• Small population

High risk factors

• Poor education

• Little money

• Low quality infrastructure

• Large, dense population

How climate changes increases risk

Warmer areas lead to more energy gained, leading to hurricanes

Some parts get wetter and more prone to flooding

Hotter areas get more droughts leading to famine

How poverty increases risk

Poor people forced to live in high risk areas, leading to people building houses in dangerous areas

How urbanisation increases risk

Some of the world’s largest cities are at risk of hazards

Densely populated areas are at greater risk

How farming increases risk

Floodplains are good for farming but are prone to flooding

Oceanic crusts

• 6-8km thick

• Heavier and denser

• Newer

• Basalt

Continental crusts

• 30-50km thick

• Lighter

• Older

• Granite

Constructive plates

Move away from each other

Volcanoes, small earthquakes

Destructive

Move towards each other

Mountains, Earthquakes, Volcanoes

Conservative

Moves alongside each other

Hills, earthquakes

Ash clouds

Ash blasted into the atmosphere

• Disrupts air transport

• Smothers farmland

• Suffocates people

Lava

Liquid magma on the Earth’s surface

• Destroys property, forests and fields

Pyroclastic flow

Deadly mix of rocks ash and gas surging quickly down volcano’s side

• Extremely dangerous

• Burns everything in path

Social reasons for living near volcanoes

• It’s scenic

• Well developed areas have good prep for minimising risk

Economic reasons for living near volcanoes

• Good for tourism

• Many jobs for mining minerals, e.g. sulphur

Environmental reasons for living near volcanoes

• Volcanic soil is fertile

• Volcanic activity is rare

How does remote sensing reduce risk from volcanoes?

GPS satellites and other machinery detect ground deformations

Some phones have GPS receivers and accelerators built in to detect movement in the ground

How does seismology reduced risk from volcanoes?

Devices are used to detect radon gas that escape from cracks in the Earth’s surface

L’Aquila: Primary impacts

300 people died and 1500 people were injured

Up to 15000 buildings were damaged, including the hospital

L’Aquila: Secondary impacts

Fewer applications for the University of L’Aquila

Transport was damaged due to landslides and rock falls

L’Aquila: Immediate responses

Temporary shelter was provided

The EU provided $550 million

L’Aquila: Long-term responses

No taxes were paid by residents of L’Aquila in 2010

University fees were dropped for 3 years

Nepal: Primary impacts

9000 people died and 22000 people were injured

7000 schools were destroyed

Nepal: Secondary impacts

Kali Gandabi river got blocked causing floods

250 people missing from Langtang

Nepal: Immediate responses

500000 temporary shelters were set up

The UN and the WHO provided medical supplies

Nepal: Long-term responses

Buildings were constructed with safety in mind

Base camp at Mt. Everest was repaired since it is an important source of Nepal’s economy

Global atmospheric circulation

Movement of air around the Earth in cells to balance the temperature.

Insolation

Incoming solar radiation

Which pressure zones do winds blow from and to?

From high pressure to low pressure

High pressure

Cold air sinks - dry skies

Low pressure

Warm air rises - rainy

Coriolis effect

Distortion of winds on the ground caused by the Earth’s rotation

Cells from north to south

Polar, Ferrel, Hadley, Hadley, Ferrel, Polar

What are tropical storms called in each area?

East Asia - typhoons

US and Caribbean - hurricanes

South Asia - cyclones

Australia - Willy-willies

What are the conditions to form a tropical storm?

From 5-30° north and south of the equator - temp are higher here so pressure is low and air rises

In the summer and autumn - sea temps are at their highest

Over warm oceans above 27°C, 60-70m deep - provides heat and moisture

What are the features of a tropical storm?

Between 482-644km wide

6-8km high

As fast as 65km/h

What is the structure of a tropical storm?

The central part is the eye, it has no rain and light wind speeds.

It is surrounded by towering cumulonimbus clouds, has heavy rain and wind speeds of up to 320km/h

How do tropical storms develop?

Air is heated above the ocean surface, causing warm air to rise rapidly.

More warm, moist air is drawn up, causing strong winds.

As it rises, it cools and condensed to form towering cumulonimbus clouds which make torrential rainfall.

Coriolis effect causes it to spin up around the eye to create an eye wall where it is most intense.

Cool air sinks in the eye so t is calmer and drier.

It travels across the ocean in the direction of the prevailing winds.

When it meets land, it loses power as there is no more moisture from the ocean to fuel it.

How might climate change affect the distribution of tropical storms?

May affect areas outside of the current hazard zones as the seas will get more warmer.

How might climate change affect the frequency of tropical storms?

It is unsure whether it will increase or decrease but the intensity will increase.

How might climate change affect the intensity of tropical storms?

Intensity may increase due to warmer temps and higher sea levels.

What are the primary effects of Typhoon Haiyan?

6,300 people died across the Philippines, Vietnam, China, and SP Islands.

Nearly 600,000 people were displaced.

There was over 400mm rain

What are the secondary impacts of Typhoon Haiyan?

Raw sewage was spread by flood waters.

14 million affected, many homeless and lost income.

Cost the government at least $5.8 billion to repair and for lost earnings.

What are the immediate responses to Typhoon Haiyan?

Over 1,200 evacuation sites were set up.

UK government sent shelter kits to families.

Philippines red cross delivered basic food aid.

What are the long-term responses to Typhoon Haiyan?

Immunised people against diseases.

UN donated financial aid, supplied and med support.

Thousands of home are being built away from areas at risk.

How to reduce the effect of tropical storms through prediction?

TV, radio and social media will broadcast storm warnings days in advance.

Scientists use satellites to predict the track of the hurricane

How to reduce the effect of tropical storms through protection?

Storm-proof building adaptation shelters, e.g. shutters over windows, made of strong concrete

Storm shelters

Sea walls and levees

How to reduce the effect of tropical storms through planning?

National awareness program - activities in school and on social media

Signposts - evacuation routes and shelters are clearly marked around the city.

Extreme weather

When weather events are significantly different from the average or usual weather pattern, and is severe or unseasonal

Weather vs Climate

Weather is day to day atmospheric condition while climate is the average

What are the different types of weather hazards in the UK?

Thunderstorms

Prolonged rainfall

Droughts and heatwaves

Snow and extreme cold

Strong winds

Somerset Levels 2014: Location

Somerset is a county in south-west England. It is bordered by the Bristol Channel, Quantock Hills and Mendip Hills

Somerset Levels 2014: Why is the area prone to flooding?

The Somerset Levels and Moors are very flat and low-lying, with many slow-flowing rivers suffering from silt. The ground becomes easily saturated

How were the Somerset level floods caused?

Caused by low pressure systems as 13 storms hit the south-west in short periods of time.

Rainfall was 3x the average and was the wettest winter in 200 years.

What were the social impacts of the Somerset level floods?

Power supplies cut

Over 600 houses flooded

16 farms evacuated

What were the economic impacts of the Somerset level floods?

Bristol to Taunton railway line closed at Bridgewater

Over 1000 livestock evacuated

Cost of damage was more than £10 million

What were the environmental impacts of the Somerset level floods?

Floodwaters were heavily contaminated with sewage and pollutants

Stagnant water needed reoxygenating before being pumped back into rivers

Large amounts of debris had to be cleared

How was the risk reduced at the Somerset Levels?

Riverbank height was raised

8km of rivers have been dredged to increase capacity

£20 million Flood Action Plan launched by Somerset County Council