These topic notes have been made for the Edexcel IGCSE Geography course using the syllabus statements as well as various other diagrams and explanations from various study sources. They are extremely detailed and cover each subtopic of topic 3. They do not just include theory but also examples tha...
3.1 (a) CHARACTERISTICS, DISTRIBUTION AND MEASUREMENT OF DIFFERENT TYPES OF
NATURAL HAZARDS------------
IMPORTANT TERMS
Term Meaning
Hazards An event that threatens or actually causes damage and destruction to people, their
property and settlements
T (Typhoon 1) How close the typhoon is (to Hong Kong)
VEI Volcanic Explosivity Index
● Volume of products
● Eruption cloud height
● Qualitative observations (“gentle” to “mega colossal”)
Richter scale ● Governed by amplitude and distance
● Not used anymore because it underestimated the size of large earthquakes
Seismic ● Compares the sizes of different earthquakes
moment ● Usually estimated from ground motion recordings of earthquakes (seismogram)
Mercalli scale Estimates the intensity of of an earthquake based on people’s experiences and
observations
Moment ● Measures energy released during an earthquake
magnitude ● Distance the fault moved and the force required to move it
Volcanic Relative measure of the explosiveness of volcanic eruptions
explosivity
index
Saffir-Simpson ● Hurricanes are measured by this scale
scale ● Wind speed and severity of damage
FOUR MAJOR CATEGORIES OF HAZARDS
Geological Climatic Biological Technological
Landslides Drought Fungi Air pollution
Earthquakes Storms - wind Viruses Radiation
Volcanic eruptions Floods Bacteria Oil spills
,TROPICAL CYCLONES
● Tropical cyclones are rotating, low pressure systems (below 950mb)
● 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 100-2000 km across the rotating clouds surround a central, calm eye
● Measured on the Saffir-Simpson Scale from 1 to 5
● They develop in tropical regions between 5° and 30° north and south of the equator
Distribution of tropical cyclones
EARTHQUAKES
● A sudden, violent shaking of the ground
● Earthquakes occur at all types of plate boundaries
● 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
● The focus is the point at which the earthquake starts below the Earth's surface
● Measured on the Richter Scale or the Moment Magnitude Scale
● The damage caused by earthquakes is measured on the Mercalli Scale
Distribution of earthquakes
, VOLCANOES
● When magma erupts onto the Earth's surface as lava
● Most volcanoes occur at constructive (divergent) and destructive (convergent) plate boundaries
● Ring of fire: A path along the Pacific Ring of Fire characterised by active volcanoes and frequent
earthquakes
● 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)
Distribution of volcanoes
3.1 (b) CAUSES OF TROPICAL CYCLONE HAZARDS------------------------------------
IMPORTANT TERMS
Term Meaning
Cumulonimbus From Latin cumulus, meaning ‘heaped’ and nimbus, meaning ‘rainstorm’ is a dense,
Cloud towering vertical cloud that forms water vapour carried by powerful upward air currents
Wind shear ● Sudden changes in wind speed and direction with increasing altitude
● Encourages the circulator motion within the cyclone
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