GCSE Geography Natural Hazards

What is a natural hazard?

A natural event that threatens people or has the potential to cause damage, destruction and death

What is a natural disaster?

When a natural hazard actually causes serious damage, destruction or loss of life

Name the three types of plate margin

Constructive (divergent), Destructive (convergent) and Conservative (transform)

What happens at a constructive plate margin?

Plates move apart; magma rises to fill the gap, creating new crust (e.g. Mid-Atlantic Ridge)

What happens at a destructive plate margin?

Oceanic plate subducts under continental plate; magma rises forming volcanoes and causing earthquakes

What happens at a conservative plate margin?

Plates slide past each other; friction builds up and is released as earthquakes (no volcanoes)

Why do earthquakes and volcanoes occur at plate margins?

The movement of tectonic plates causes friction, pressure and melting of rock

What is the focus of an earthquake?

The point underground where the earthquake starts

What is the epicentre of an earthquake?

The point on the Earth’s surface directly above the focus

How is the magnitude of an earthquake measured?

Using the Moment Magnitude Scale (or Richter Scale) – higher number = stronger earthquake

What are the primary effects of an earthquake?

Immediate effects caused directly by the ground shaking (e.g. buildings collapse, roads crack, people injured)

What are the secondary effects of an earthquake?

Effects that happen later as a result of the primary effects (e.g. fires, tsunamis, disease, homelessness)

Name three factors that affect the impact of a tectonic hazard

Level of development (HIC vs LIC), population density, distance from epicentre, building quality, prediction/preparation

What is a tropical storm?

A large, rotating storm system with high winds and heavy rainfall that forms over warm tropical oceans

What conditions are needed for a tropical storm to form?

Ocean temperature of at least 27°C, depth of warm water at least 60–70 m, and the Coriolis effect

Describe the structure of a tropical storm

Calm eye in the centre, surrounded by the eyewall (strongest winds and heaviest rain), then spiral rain bands

What is the Saffir-Simpson scale used for?

To measure the strength of tropical storms (Category 1 to 5 based on wind speed)

Name three primary effects of a tropical storm

High winds damage buildings, heavy rainfall causes flooding, storm surges flood coastal areas

Name three secondary effects of a tropical storm

Landslides, contaminated water leading to disease, loss of crops, homelessness, economic disruption

What is climate change?

A long-term change in the Earth’s average temperature and weather patterns

Name two natural causes of climate change

Volcanic eruptions (ash blocks sunlight) and changes in the Earth’s orbit / axial tilt (Milankovitch cycles)

Name two human causes of climate change

Burning fossil fuels (releases CO₂) and deforestation (reduces CO₂ absorption and releases stored carbon)

What is the greenhouse effect?

Greenhouse gases (CO₂, methane) trap heat in the atmosphere, keeping the Earth warm enough for life

What is the enhanced greenhouse effect?

Extra greenhouse gases from human activity trap more heat, causing global temperatures to rise

Name three possible effects of climate change

Rising sea levels, more extreme weather (storms, droughts, floods), melting ice caps, changing ecosystems

What is mitigation in the context of climate change?

Actions that reduce or prevent the emission of greenhouse gases (e.g. renewable energy, reforestation)

What is adaptation in the context of climate change?

Actions that help people cope with the effects of climate change (e.g. sea walls, drought-resistant crops)

Why do people continue to live in areas at risk from natural hazards?

Fertile soils near volcanoes, tourism, poverty (cannot afford to move), family/historical ties, job opportunities

Name three ways people can prepare for tectonic hazards

Earthquake-proof buildings, early warning systems, evacuation plans, education and drills, emergency supplies