Effects of Earthquakes & Volcanoes (Cambridge (CIE) IGCSE Geography)

Effects of Earthquakes & Volcanic Eruptions

The impacts of earthquakes and volcanic eruptions can be categorised into:

• Primary hazards: these are a direct result of the earthquake or eruption

• Secondary hazards: these occur as a result of the primary effects

Factors affecting the impacts of earthquakes and volcanic eruptions

• All earthquakes and volcanic eruptions are unique

• The impacts that they have depend on a range of factors both human and physical

Human factors affecting earthquake impacts

• Building construction and design 

  • Poorly constructed buildings with poor-quality building materials are more likely to collapse

  • Higher buildings amplify the shockwaves and are more likely to collapse

• Building density

  • Where buildings are close together, they are more likely to damage or destroy other buildings if they fall

• Population density

  • The higher the density population, the more people are likely to be injured or killed

• Preparation

  • Earthquake drills can reduce the impact 

Physical factors affecting earthquake impacts

• Magnitude

  • The amount of energy released by the earthquake

  • Usually, the higher the magnitude, the greater the impact

• Geology

  • Some rocks are more prone to liquefaction; others provide stronger foundations for buildings

• Distance from the epicentre

  • The closer somewhere is to the epicentre, the stronger the shock waves will be

• Depth

  • Shallower earthquakes mean less energy is absorbed by the crust before the shockwaves reach the surface

Human factors affecting volcano impacts

• Proximity of population

  • How close populations are to the volcano

  • The closer people are to the volcano, the more likely they are to be affected by lava flow and ash

• Planning and preparation

  • Where authorities have planned exclusion zones and evacuation plans, the impact may be reduced

Physical factors affecting volcano impacts

• Magnitude

  • The size and strength of the eruption

  • Usually, the higher the magnitude, the greater the impact 

• Type of volcano

  • Composite (strato-volcanoes) tend to be more explosive and less predictable than shield volcanoes 

• Amount of ash ejected into the atmosphere

  • Ash in the atmosphere can impact areas many hundred kilometres away and can affect the global climate

Effects of earthquakes and volcanic eruptions

• Although the characteristics of earthquakes and volcanic eruptions are very different, many of the impacts are similar

• Impacts include:

  • Loss of life and injury

    • This may be immediate through falling buildings or ash fall

    • Alternatively, it may be in the days and weeks after the event due to unclean water or disease

  • Collapse or destruction of buildings

    • This leads to people being homeless for months and even years after the event

  • Transport network

    • Roads, bridges and railways may be damaged or destroyed

    • This can impact the speed at which aid can get to affected areas

  • Loss of jobs and businesses

    • This impacts the economy when factories and offices are destroyed or damaged

  • Loss of crops

    • Leads to food shortages and affects farmers income

  • Power and water supply damaged

    • This affects the supply of clean water and electricity

  • Damage to the environment

    • Loss of vegetation and habitat

    • The effects on the climate of ash in the atmosphere

  • Closure of airports

    • It is dangerous for jet planes to fly through ash clouds due to possible engine failure, so flights are cancelled