Edexcel IGCSE Geography Anatomy of Natural Hazards PDF

Head to www.savemyexams.com for more awesome resources Edexcel IGCSE Geography Your notes Anatomy of Natural Hazards Contents Types of Hazards Tropical Cyclones Tectonic Hazards...

Head to www.savemyexams.com for more awesome resources Edexcel IGCSE Geography Your notes Anatomy of Natural Hazards Contents Types of Hazards Tropical Cyclones Tectonic Hazards Page 1 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Types of Hazards Your notes Anatomy of natural hazards Natural hazards A hazard is an event which has the potential to cause harm to the environment, people or the economy A natural hazard is an event caused by environmental processes A disaster occurs when harm actually occurs to the environment, people or the economy Natural hazards can be categorised by their causes Tectonic & Geological Climatic & Meteorological Biological Earthquake Storms Pests Volcanic eruption Floods Diseases Landslides Droughts Tsunami Tornadoes Natural events only become hazards and disasters due to their impact on people, the environment or the economy Natural hazards can also be categorised in a range of other ways: Magnitude - the strength/power of the event Frequency - how often the event occurs Size - the area covered by the hazard Duration - the time a hazard event lasts Location - where a hazard event occurs Hazard risk refers to the likelihood of an event causing harm to people, the environment or the economy Different locations have different levels of vulnerability This refers to location features which affect how susceptible an area is to a hazard event Page 2 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Tropical cyclones Tropical cyclones are rotating, low-pressure systems (below 950mb) Your notes They are known as hurricanes, cyclones and typhoons in different areas of the world Characteristics include: heavy rainfall high wind speeds (over 119 kmph) high waves and storm surges Measuring between 100-2000km across the rotating clouds surround a central, calm eye The magnitude of tropical cyclones is measured on the Saffir-Simpson Scale from 1 to 5 They develop in tropical regions between 5o and 30o north and south of the equator Map showing the global distribution of tropical cyclones Earthquakes An earthquake is a sudden, violent shaking of the ground Earthquakes occur at all types of plate boundaries Page 3 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Earthquakes are the result of pressure building when tectonic plates move The epicentre is the point on the Earth's surface directly above the focus Your notes The focus is the point at which the earthquake starts below the Earth's surface The magnitude of earthquakes is measured on either the Richter Scale or the Moment Magnitude Scale The damage caused by earthquakes is measured on the Mercalli Scale Map showing global earthquake distribution Volcanoes Volcanoes form when magma erupts onto the Earth's surface as lava Most volcanoes occur at constructive (divergent) and destructive (convergent) plate boundaries The majority of active volcanoes are located around the rim of the Pacific Ocean called the 'Ring of Fire' Hotspots occur away from plate boundaries and are plumes/columns of magma which escape through the Earth's crust The magnitude of a volcanic eruption is measured on the Volcanic Explosivity Index (VEI) Page 4 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes Map showing active volcano distribution Examiner Tips and Tricks When describing the distribution of hazards from a map ask yourself the following questions; What is the general pattern? Does the pattern relate to anything else for example the location of plate boundaries? Are they near the equator or further away? Are they inland or coastal? Use map features to help with your description - place names, compass rose, latitude and longitude Page 5 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Tropical Cyclones Your notes Causes of tropical cyclone hazards Tropical cyclones are low-pressure areas (less than 950mb) Tropical Cyclones require specific conditions to form: Sea surface temperatures over 27°C Between 5° and 20° north and south of the equator Low wind shear A deep layer of humid air Stages of tropical cyclone formation In the right conditions, a tropical cyclone can form rapidly. The formation follows several stages: Warm, moist air rapidly rises forming an area of low pressure Air from high-pressure areas rushes in to take the place of the rising air This air then rises forming a continuous flow of rising air As the air rises it cools and condenses. This releases heat energy which helps to power the tropical cyclone Air at the top of the storm goes outwards away from the centre of the storm The Coriolis force causes the rising air to spiral around the centre. Some of the air sinks in the middle of the storm forming the cloudless, calm eye. The tropical cyclone moves westwards from its source When a tropical cyclone makes landfall or moves over an area of cold water it no longer has a supply of warm, moist air and it loses speed and temperature. Rainfall and winds decrease Features of tropical cyclone Tropical cyclones have several features including: Heavy rainfall High wind speeds (over 74kmph) Page 6 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Storm surges Calm eye Your notes Highest winds and heaviest rain in the wall of the eye Diameter up to 1000 km The formation of a tropical cyclone Worked Example Explain the formation of a tropical cyclone (4 Marks) Identify the command word The command word is 'explain' Page 7 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources The focus of the question is 'the formation of a tropical cyclone' Questions such as this are easiest to complete if you view them as a series of steps Answer: Your notes Warm seawater (27°C or over) around the tropics (1) There are high levels of evaporation and condensation of water vapour from warm water leading to cumulonimbus cloud formation (1) The high levels of evaporation and condensation of water vapour provide energy for strong winds (1) Strong Coriolis Force close to the equator makes winds spin and moves them away from the equator (1) The tropical cyclones move westwards due to east-west winds in the tropics and strengthen as they move over warm waters (1) The tropical cyclone dissipates when it reaches land or outside the tropics as the supply of warm, moist air is cut off (1) Examiner Tips and Tricks Remember conditions such as warm oceans and the Coriolis Force exist at all times but tropical cyclones do not form all the time. It is the combination of all the right conditions coming together which leads to tropical cyclone formation. Page 8 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Tectonic Hazards Your notes Plate boundaries Types of plate boundary Volcanic eruptions and earthquakes most commonly occur at or near plate boundaries There are four main types of plate boundaries: Constructive (divergent) Destructive (convergent) Collision Conservative (transform) Constructive (divergent) plate boundary At the constructive boundary, the plates are moving apart The Mid-Atlantic Ridge is an example of a constructive plate boundary Both volcanic eruptions and earthquakes can occur at this type of plate boundary Constructive (Divergent) plate boundary Page 9 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Destructive (convergent) plate boundary At a destructive (convergent) plate boundary, the plates are moving together Your notes The denser, heavier oceanic plate subducts under the lighter, less dense continental plate The boundary between the Nazca plate and the South American plate is an example Both volcanic eruptions and earthquakes occur at this type of plate boundary Destructive (Convergent) Plate Boundary Collision boundary At a collision boundary, two plates of similar density move towards each other Neither is dense enough to subduct so the land is pushed upwards This process forms fold mountains such as the Himalayas Earthquakes are the main hazard at this type of plate boundary Page 10 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes Collision Boundary Conservative (transform) boundary At a conservative (transform) boundary, the plates move past each other in opposite directions or in the same direction at different speeds Earthquakes are the only hazard at this type of boundary Page 11 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes Conservative (Transform) Boundary Examiner Tips and Tricks Draw each of the plate boundaries and add annotations to outline the processes. This will help you to remember what happens at each one. Causes of volcanic hazards Volcanoes occur at constructive (divergent), destructive (convergent) plate boundaries and hot spots Volcanoes do not occur at collision boundaries or conservative (transform) boundaries Volcanoes at constructive boundaries At a constructive (divergent) boundary, the tectonic plates are moving away from each other: Constructive plate boundaries often occur under the sea/ocean The lava escapes through the gap left as the plates move apart The lava cools and hardens, forming a new crust Page 12 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources At constructive plate boundaries, the lava tends to be runny and eruptions are less explosive These types of eruption form shield volcanoes, which have gently sloping sides Your notes Volcanoes at destructive boundaries At a destructive (convergent) boundary, the tectonic plates are moving towards each other: The heavier, denser oceanic plate subducts under the lighter continental plate In the subduction zone, the two plates come together, causing friction Friction causes heat and the plate material melts, forming magma The magma rises to the surface through cracks in the crust The cooling lava and ash build up, forming a volcano At destructive plate boundaries, the lava tends to be sticky and produces explosive eruptions These eruptions tend to form composite or stratovolcanoes Volcanoes at hot spots At a hot spot, the tectonic plate passes over a plume of magma: The magma rises to the surface through cracks in the crust As the tectonic plate moves slowly over the magma plume, a line of islands may form, e.g. Hawaii Page 13 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes Hot spot and island formation Volcano primary and secondary hazards Volcanic eruptions only become hazards when they affect people The hazards from the volcanic eruption itself are primary hazards: Ash Pyroclastic flow Lava flow Gas emissions Volcanic bombs The hazards created that happen as a result of the primary hazards are secondary hazards: Lahars Page 14 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Acidification Landslides Your notes Climate change Fires Floods Causes of earthquake hazards Earthquakes & plate boundaries Earthquakes can occur anywhere but mostly occur at or near plate boundaries Earthquakes happen at all plate boundaries - constructive (divergent), destructive (convergent), collision and conservative (transform) At a constructive (divergent) plate boundary, earthquakes tend to be weaker as the plates are moving apart At destructive (convergent), collision and conservative (transform) plate boundaries earthquakes tend to be stronger Earthquakes primary & secondary hazards The primary hazard of an earthquake is the ground shaking all other hazards then follow on from this as secondary hazards Secondary hazards can include: Collapse of buildings and other structures Landslides Gas leaks Fires Soil liquefaction Subsidence Mudflows Tsunami Earthquake sequence The sequence of an earthquake is the same regardless of the boundary at which it happens: Page 15 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources As the tectonic plates move, they can get stuck Pressure builds as the plates continue to try to move Your notes Eventually, the plates jolt free and the pressure is released as energy The point at which the earthquake starts is the focus The epicentre is the point directly above the focus on the earth's surface The energy passes through the Earth's crust as waves which is the earthquake Earthquakes can happen as a result of human activity such as drilling into the crust or mining Examiner Tips and Tricks When describing the processes leading to an earthquake, volcanic eruption or tropical cyclone, it is helpful to write the formation down as a sequence of steps. This will make the processes easier to remember. Page 16 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers