Geography - Natural Hazards

• Natural hazard


  A natural event that threatens people or has the potential to cause damage or death
• Examples of natural hazards

  • Earthquake
  • Volcanic eruption
  • Tropical storm
• Factors affecting hazard risk


  • Nearby population size
  • Frequency of hazards
  • The area's development
  • Preparation of the people
  • Climate change
• Plate tectonics theory


  The Earth's crust is separated into different plates, and the movement of these plates is affected by convection currents within the mantle
• Earthquakes and volcanic eruptions have a clear correlation to plate margins globally
• Types of plate margins


  • Constructive (plates pull apart, causing magma to flood to the surface, forming shield volcanoes)
  • Destructive (plates moving towards each other causes the denser plate to be subducted, causing friction build-up which can cause earthquakes, and magma from the melted plate rising to the surface, forming a composite volcano)
  • Conservative (adjacent plates scrape past each other, resulting in friction build-up, or the plates lock together, building strain, both causing earthquakes when released, but due to the lack of magma, no volcanoes)
• Primary effects of a volcano


  • People killed
  • Farmland/buildings destroyed
  • Communications damaged or disrupted
• Secondary effects of a volcano


  • Spread of disease from lack of clean water/sewers
  • Hospitals overwhelmed
  • Shortage of basic facilities
  • Reduced income/economic impact
• Immediate responses to a volcano/tectonic hazard


  • Exclusion zone established
  • Abandoning dangerous cities
  • Evacuating to safety
  • Emergency shelters
• Long-term responses to a volcano/tectonic hazard


  • New monitoring equipment
  • Infrastructure rebuilt
  • Tourism industry expanded
  • Replace farmland
• L'Aquila, Italy in 2009 and Nepal 2015 show the differing levels of effect and response to an earthquake in contrasting levels of wealth
• Reasons why people continue to live in areas of tectonic hazard


  • Already Feel Safe
  • Job Opportunities
  • Natural Resources
  • Wealth Opportunities
  • Poverty/Inability
  • Religion and Heritage
• Ways to reduce earthquake/tectonic hazard risk


  • Monitoring (Radon gas released, foreshocks, seismic activity, animal behaviour)
  • Prediction (Areas of past earthquakes marked, but no earthquakes have been accurately predicted)
  • Protection (Buildings reinforced, rolling weights to counteract shock waves, reinforced, deep, lattice foundations, fire resistant materials, all of which are too expensive for LIC's to afford)
  • Planning (Furniture fastened to keep stable, disable mains supplies, prepare emergency supplies, practice drills on a semi-regular basis, with more money, the more preparation can be performed)
• The atmospheric circulation pattern is divided into distinct cells (Hadley, Ferrel, Polar), areas with rising air have low pressure (the Equator and 60o), areas with sinking air have high pressure (30o and poles), and winds travel from areas of high pressure to low pressure
• Tropical storms


  Form between 30o north and south of the Equator, but cannot cross it, moving in the direction of the poles instead. They cannot form on the Equator, due to the lack of Coriolis Force (Earth's spin), also relying on a rising current of moist air, as well as ocean surface temperatures of at least 26.5oC, and a low wind shear (direction/changes in speed), meaning they can only form in this region of atmospheric circulation
• Formation of tropical storms

  Eye at the centre, where it is calm, with air circulating around it, to the eye wall, which is the most intense part, where wind strength increases, the rain bands that stretch out, and the storm surge in the centre, caused by the storing winds of the eye wall, and the dense cirrus canopy on the top
• Climate change


  Causes tropical storms to form over a wider area, have more powerful winds, and be larger, due to more heated, moist air, and more frequent, due to the consistently high surface ocean temperatures
• Typhoon Haiyan in the Philippines in 2013 shows the effects and responses to tropical storms
• Ways to reduce the effects of tropical storms


  • Monitoring (Satellite, radar technology)
  • Prediction (Equipment to predict based off data, National Hurricane Centre)
  • Protection (Design building to be able to withstand storms, reinforced concrete stilts, metal shutters over the windows)
  • Planning (Practice storm drills, have evacuation plans, have shelters to hide in, have supplies to distribute quickly and easily)
• Types of weather hazard the UK can experience


  • Heavy rain and strong winds, can lead to flooding and tree disruption
  • Snow and ice, leads to traffic problems
  • Droughts, can impact crop growth and hosepipe bans
  • Thunderstorms, lightning causes fires and property damage
  • Heat waves, can build up pollution and transport systems can be damaged
• The 2018 heatwave in Britain was caused by high pressure, leading to hot and dry tropical air, little cloud, warm conditions, blocking any cool air from the Atlantic, reducing the amount of rainfall all over Europe
• Impacts of the 2018 heatwave in Britain


  • Socially (700 deaths, heat stroke and dehydration, London Underground unbearable, hosepipes banned)
  • Economically (Agriculture impacted, higher food prices, increased tourism, water supplies dried up)
  • Environmentally (Dry conditions, forest fires, air pollution, cracked earth, rivers and lakes lower)
• Management strategies to reduce risk of weather events


  • Hosepipe bans
  • Speed restrictions for trains
  • Refuse collectors start earlier in the day
  • Altered working hours
• Evidence that weather is becoming more extreme includes increased extremes in temperature and powerful storms
• We are near the peak temperatures of the Quaternary period, thus the temperatures of the Earth are naturally rising, increasing global warming's effect
• Causes of climate change


  • Natural (Milankovitch cycle (Change in orbit shape, angle of tilt and wobble of Earth), solar activity/flares, volcanic activity)
  • Human (Burning fossil fuels, cattle/rice farming and landfills)
• Effects of climate change


  • Rising temperatures
  • Extinction of species/habitats
  • Rising sea levels
  • Increased natural disasters
  • Food insecurity
• Ways to manage climate change


  • Mitigation (Alternative energy production, carbon capture, planting trees, international agreements)
  • Adaptation (Changing agricultural systems, reducing risk from rising seas, managing water supplies)