The challenge of natural hazards

What is a natural hazard?

A natural event that poses a threat to people, property, or the environment

What are the three main types of natural hazard?

Tectonic, atmospheric, geomorphological

Give an example of a tectonic hazard.

Earthquake, volcanic eruption

Give an example of an atmospheric hazard.

Tropical storm, drought, extreme temperatures

Give an example of a geomorphological hazard.

Flooding, landslide, avalanche

What factors affect hazard risk?

Vulnerability, capacity to cope, nature of hazard, population density

What does 'vulnerability' mean in hazard risk?

How exposed people are to harm from a hazard

What is plate tectonics theory?

Earth's crust is divided into tectonic plates that move due to convection currents in the mantle

Where do most earthquakes and volcanoes occur?

Along plate boundaries

What is a constructive plate margin?

Where two plates move apart and new crust is formed

Give an example of a constructive margin.

Mid-Atlantic Ridge

What happens at a constructive margin?

Gentle volcanic eruptions, shallow earthquakes, formation of new oceanic crust

What is a destructive plate margin?

Where two plates move towards each other and one is subducted

What happens at a destructive margin?

Violent earthquakes, explosive volcanoes, deep ocean trenches

Give an example of a destructive margin.

Nazca Plate subducting under South American Plate (Chile)

What is a conservative plate margin?

Where two plates slide past each other

What happens at a conservative margin?

Earthquakes (no volcanoes), plates lock then suddenly slip

Give an example of a conservative margin.

San Andreas Fault, California

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

Fertile volcanic soil, geothermal energy, minerals, tourism, established communities, jobs

What are primary effects of a tectonic hazard?

Immediate impacts caused directly by the hazard (e.g., building collapse, deaths, injuries)

What are secondary effects of a tectonic hazard?

Indirect impacts occurring later (e.g., fires, tsunamis, disease, unemployment)

What are immediate responses to a tectonic hazard?

Actions taken straight after the event (e.g., rescue, emergency aid, medical care)

What are long-term responses to a tectonic hazard?

Actions taken months or years later (e.g., rebuilding, improving infrastructure, prevention measures)

How can monitoring reduce tectonic hazard risks?

Using equipment (seismometers, tiltmeters) to detect warning signs

How can prediction reduce tectonic hazard risks?

Using data to forecast when/where hazards might occur, allowing preparation

How can protection reduce tectonic hazard risks?

Building earthquake-resistant structures, tsunami walls, automatic shut-off systems

How can planning reduce tectonic hazard risks?

Emergency drills, evacuation routes, education, land-use zoning

When and where did the Chile earthquake occur?

27 February 2010, off the coast of central Chile near Concepción

What was the magnitude of the Chile 2010 earthquake?

8.8 on the Richter scale

What plate boundary caused the Chile earthquake?

Destructive margin (Nazca Plate subducting beneath South American Plate)

What were the primary effects of the Chile 2010 earthquake?

Over 500 deaths, 12,000 injured, 220,000 homes destroyed, roads and bridges damaged, power cuts, 1.5m high tsunami

What were the secondary effects of the Chile 2010 earthquake?

1,500 km of roads damaged, coastal destruction from tsunami, $30 billion economic damage, fire at chemical plant

What were the immediate responses to the Chile 2010 earthquake?

Emergency services deployed rapidly, international rescue teams, temporary shelters, power restored within 24 hours

What were the long-term responses to the Chile 2010 earthquake?

Reconstruction plan, housing rebuilt quickly, improved building regulations, enhanced tsunami warning system

Why did Chile cope relatively well with the earthquake?

High-Income Country (HIC), strict building codes, wealth, experience with earthquakes, good emergency planning

When and where did the Nepal earthquake occur?

25 April 2015, epicentre near Kathmandu, Nepal

What was the magnitude of the Nepal 2015 earthquake?

7.9 on the Richter scale (followed by 7.3 magnitude aftershock on 12 May)

What plate boundary caused the Nepal earthquake?

Collision boundary (Indian Plate colliding with Eurasian Plate)

What were the primary effects of the Nepal 2015 earthquake?

Over 9,000 deaths, 20,000 injured, 3 million homeless, buildings destroyed (including UNESCO heritage sites), avalanches on Mount Everest killed 19

What were the secondary effects of the Nepal 2015 earthquake?

Landslides blocked roads, disease outbreaks, tourism industry collapsed, $5 billion economic loss, food shortages, 7,000 schools destroyed

What were the immediate responses to the Nepal 2015 earthquake?

International search and rescue teams, field hospitals, temporary shelters, aid donations, helicopters evacuated injured

What were the long-term responses to the Nepal 2015 earthquake?

Slow rebuilding (took years), improved building codes, roads repaired, risk assessments, tourism recovery, international funding

Why did Nepal suffer more than Chile?

Low-Income Country (LIC), poor infrastructure, weak buildings, mountainous terrain, limited emergency services, reliance on aid

Compare death tolls: Chile vs Nepal.

Chile: ~500 deaths; Nepal: ~9,000 deaths

Compare building standards: Chile vs Nepal.

Chile had strict earthquake-resistant codes; Nepal had old, poorly constructed buildings

Compare wealth: Chile vs Nepal.

Chile is a HIC with resources; Nepal is a LIC with limited resources

Compare emergency response speed: Chile vs Nepal.

Chile responded quickly with own resources; Nepal relied heavily on slower international aid

What is a tropical storm?

An intense low-pressure weather system with strong winds (over 119 km/h) and heavy rain

Where do tropical storms form?

Over warm tropical oceans (above 27°C), between 5° and 30° latitude

What are tropical storms called in different regions?

Hurricanes (Atlantic), Cyclones (Indian Ocean), Typhoons (Western Pacific)

What conditions are needed for tropical storm formation?

Sea temperature above 27°C, low wind shear, ocean depth over 70m, between 5-30° latitude (for Coriolis effect)

Describe the formation of a tropical storm.

Warm air rises rapidly, condensation releases latent heat, low pressure draws in more air, Coriolis effect causes spin, storm intensifies

What is the structure of a tropical storm?

Eye (calm centre), eyewall (strongest winds and rain), spiraling rainbands

What is the eye of a tropical storm?

The calm, clear centre with low pressure and light winds

What is the eyewall?

Ring of towering clouds around the eye with the most intense winds and heaviest rainfall

How might climate change affect tropical storms?

Could increase intensity, alter distribution, possibly change frequency, worsen storm surges (sea level rise)

What are primary effects of tropical storms?

Strong winds destroy buildings, heavy rain causes flooding, storm surges, deaths and injuries

What are secondary effects of tropical storms?

Landslides, disease (contaminated water), homelessness, economic loss, food/water shortages

What are immediate responses to tropical storms?

Evacuation, emergency shelters, rescue operations, emergency aid (food, water, medical care)

What are long-term responses to tropical storms?

Rebuild infrastructure, improve flood defenses, restore services, economic recovery programs

How can monitoring reduce tropical storm effects?

Satellite tracking, weather stations, aircraft reconnaissance provide early warnings

How can prediction help with tropical storms?

Accurate forecasts allow time for evacuation and preparation, saving lives

How can protection reduce tropical storm impacts?

Storm-resistant buildings, sea walls, raised foundations, flood defenses

How can planning reduce tropical storm damage?

Evacuation routes, education programs, emergency drills, land-use planning (avoid flood-prone areas)

What types of weather hazards affect the UK?

Heavy rain and flooding, droughts, heatwaves, snow and ice, strong winds/storms

Give an example of extreme weather in the UK.

Somerset Levels floods (2014), 2018 heatwave, Beast from the East (2018)

What evidence suggests UK weather is becoming more extreme?

More frequent flooding, record high temperatures, unpredictable weather patterns, intense storms

What is climate change?

Long-term change in global or regional climate patterns, especially temperature and precipitation

What is the Quaternary period?

The last 2.6 million years, including cycles of ice ages and warmer interglacial periods

What evidence exists for past climate change?

Ice cores, tree rings, pollen analysis, temperature records, historical sources, retreating glaciers

What are natural causes of climate change?

Milankovitch cycles (orbital changes), volcanic eruptions, solar output variations

What are human causes of climate change?

Burning fossil fuels (CO₂), deforestation, agriculture (methane from livestock, rice paddies)

What are the effects of climate change on people?

Food and water shortages, forced migration, health risks (disease spread), economic impacts

What are the effects of climate change on the environment?

Sea level rise, ice melt, extreme weather, habitat loss, species extinction

What is mitigation in managing climate change?

Reducing the causes—cutting greenhouse gas emissions, renewable energy, carbon capture

What is adaptation in managing climate change?

Responding to impacts—flood defenses, drought-resistant crops, water management

Give two examples of mitigation strategies.

Switching to renewable energy (solar, wind), reforestation/afforestation, carbon taxes, energy efficiency

Give two examples of adaptation strategies.

Building sea walls, developing drought-resistant crops, water conservation, changing agricultural practices

Why is international cooperation needed for climate change?

It's a global problem requiring coordinated action; agreements like Paris Agreement set targets

What is the Paris Agreement?

International treaty aiming to limit global warming to below 2°C (ideally 1.5°C) above pre-industrial levels

What is the general atmospheric circulation model?

Global system of wind and pressure belts redistributing heat from equator to poles

What are the three main atmospheric cells?

Hadley cell, Ferrel cell, Polar cell

Where is the Hadley cell located?

Between equator and 30° latitude

What happens in the Hadley cell?

Warm air rises at equator, moves to 30° latitude, sinks creating high pressure

What is the Coriolis effect?

Deflection of winds and ocean currents caused by Earth's rotation

Why is the Coriolis effect important for tropical storms?

It causes the spinning motion needed for storm formation

Why don't tropical storms form at the equator?

Coriolis effect is too weak (need at least 5° latitude)

What happens when a tropical storm moves over land?

Loses energy source (warm water), weakens, causes heavy rain and wind damage

What happens when a tropical storm moves over cool water?

Loses energy, weakens and eventually dissipates