3.1.1.1 & 3.1.1.2 Natural & Tectonic Hazards

• Natural Hazard


  A natural process which could cause death, injury or disruption to humans, or destroy properties and possessions.

  
  

  (Pose major risk to people and property)
• Natural Disaster


  A natural hazard event that has already happened
• Main 3 types of Natural Hazards

  1. Geological hazards: caused by land & tectonic processes (volcanoes, earthquakes, landslides, mudflows)
  2. Atmospheric hazards: caused by weather & climate (Tropical storms, tornadoes, droughts)
  3. Hydrochloric hazards: caused by the movement of water on land (Flooding)
• Hazard Risk


  The probability of people being affected by a hazard in a particular area
• 3 Factors Affecting Hazard Risk

  1. Capacity to cope: better population = lower risk, HICs have money to build defences & evacuate
  2. Vulnerability: more people exposed in an area = greater probability of getting affected
  3. Nature of Natural Hazards: TYPE- risk of some hazards > others, FREQUENCY- natural hazards that occur more often have greater risks, MAGNITUDE- more severe = greater effects
• Primary effects


  The immediate impacts caused by the hazard itself e.g injuries/deaths
• Secondary effects 


  Impacts that happen later on, often result from the primary effects e.g food & water shortages
• Immediate responses


  Action taken straight away to save lives, prevent human suffering or mitigate property damage e.g evacuating people
• Long-term responses


  Action that goes on for months/years after a disaster e.g rebuilding buildings, roads, railways and bridges
• Inner core


  The hottest part of the Earth, solid and made up of iron and nickel with temperatures of up to 5,500°C
• Outer core


  The layer surrounding the inner core, a liquid layer also made up of iron and nickel
• Mantle


  The thickest section of the Earth at approximately 2,900 km, made up of semi-molten rock called magma
• Crust


  The outer layer of the Earth, a thin layer between 0 - 60 km thick, the solid rock layer upon which we live
• Continental crust


  The surface of the Earth's crust found underneath large land masses
• Oceanic crust


  The surface of the Earth's crust found underneath the oceans, forming the ocean floor
• Tectonic plates


  A set of adjacent, slow-moving plates which make up the Earth's crust
• Convection currents


  Movement within the Earth's mantle caused by the heat of the core
• Slab pull


  Occurs when older, denser tectonic plates sink into the mantle, pulling newer and less dense sections of plate along behind
• Ridge push


  The new crust formed at divergent plate margins is less dense than the surrounding crust and so it rises to form oceanic ridges
• Plate margin


  The region where two or more tectonic plates meet, a zone of intense seismic activity
• The movement of the plates and the activity inside the Earth, is called the theory of plate tectonics
• Oceanic crust


  The surface of the Earth's crust found underneath the oceans, forming the ocean floor
• Continental crust


  The surface of the Earth's crust found underneath large land masses
• Oceanic crust is denser than continental crust and can be subducted
• Continental crust is generally older than oceanic crust and is less often destroyed
• Plate margin


  The region where two or more tectonic plates meet. It is a zone of intense seismic activity
• Earthquakes are found along all types of plate margins
• Volcanoes only occur at constructive and destructive plate margins
• Ring of fire


  A group of volcanoes that are located along the plate margin of the Pacific plate
• Hot spot


  A location where volcanic activity occurs, forming an arc of volcanic islands like Hawaii
• Plate margins

  • Destructive
  • Constructive
  • Conservative
• Destructive plate margin


  1. Two tectonic plates move towards one another

  2. Oceanic crust forced to sink back into the mantle

  3. Continental crust rises above

  4. Volcanoes and earthquakes found here
• Subduction


  When one crustal plate is forced beneath the other
• Composite volcano


  Magma escapes through weaknesses in the rock and rises up
• Collision margin


  When two continental plates collide, neither can sink and so the land buckles upwards to form fold mountains
• Constructive plate margin


  1. Tectonic plates move apart

  2. Magma from the mantle rises up to make new land in the form of a shield volcano

  3. Movement of plates over the mantle can cause earthquakes
• Conservative plate margin


  1. Plates move past each other or are side by side moving at different speeds

  2. Friction occurs and plates become stuck

  3. Pressure builds up and is then released, causing an earthquake

  4. No volcanoes
• Earthquakes are the sudden violent shaking of the ground
• Earthquakes are caused by the release of built-up pressure at plate margins
• Earthquakes can destroy buildings and infrastructure, with devastating and deadly effects