Topic 3: Hazardous Environments
Hazardous Environments.pdf
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
Hazardous Environments.pdf
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
