Geography Notes Option D: Hazards and Disasters
IB Geography — Option D: Hazards and Disasters
Definition:
Term Definition
Disaster A major hazard event that causes widespread disruption to a community or region that
the affected community is unable to deal with adequately without outside help.
Hazard A threat that has potential to cause loss of life, injury, property damage, socio-economic
disruption or environmental degradation.
Hazard event The occurrence of a hazard, the effects of which change demographic, economic and/or
environmental conditions.
Risk The probability of a hazard event causing harmful consequences (expected losses of in
terms of deaths, injuries, property damage, economy and environment).
Vulnerability The susceptibility of a community to a hazard or to the impacts of a hazard event.
1. Characteristics of hazards
Characteristics
Explain the characteristics and spatial distribution of the following hazards.
• Earthquakes/Volcanoes
- earthquake: sudden, violent shaking of the earth’s surface
- spatial distribution:
- regional
- tsunamis
- focus (beneath ground), epicenter (surface)
- occur in clearly defined linear patterns
- locations generally follow plate boundaries
- predictability:
- temporally largely unpredictable
- spatially predictable
- observing crustal movement of plates (uplift, subsidence, ground tilt)
- change in rock stress or electrical resistivity
- anomalies in magnetic field of earth
- strange and abnormal animal behavior
- historic trends and micro earthquake activity
- hazard zone mapping
- frequency:
- frequent in prone regions
- intervals largely unpredictable
- magnitude
- measured by Richter Scale
- Mercalli Scale
- intensity value to measure earthquake effect
- duration:
- for tens of seconds
- aftershocks last for extended period
- usually the longer the fault the longer the quake
- dependent on type of rock, magnitude, distance from epicenter
- speed of onset
- rapid, immediate
- factors affecting damage
1
, Geography Notes Option D: Hazards and Disasters
- Physical
- strength and depth of earthquake
- number of aftershocks
- time of day
- duration of shaking
- distance from epicenter
- type of rocks and sediments (liquefaction)
- occurrence of secondary hazards
- height above sea-level
- Human
- population density
- type of building
- economic development
- emergency and relief services
- preparedness of people
- dealing with earthquakes
- improving forecasting and warning systems
- improving building design, locations, regulations and quality monitoring
- occur along the boundaries of the tectonic plates that make up the earth’s crust
- can be caused by human activities such as: nuclear testing, building large dams, drilling for oil and coal mining
• Hurricanes/Cyclones/Typhoon
- name:
- hurricanes/tropical storms (Atlantic Ocean)
- typhoons (Pacific Ocean)
- tropical cyclones (Indian Ocean)
- necessary conditions of formation
- tropical depression (intense low-pressure system)
- warm tropical oceans (>26.5’C)
- disturbance in lower atmosphere
- Cariolis force determines direction of rotation of cyclone
- above Tropic of Capricorn, below Tropic of Cancer, away from equator
- temperature over 27 degree celsius to a depth of 60 meters
- low pressure area has to be far enough away from the equator so that the force that caused by the rotation
of the earth creates rotation in the rising air mass
- conditions must be unstable: some tropical low-pressure systems develop into hurricanes, but not all
- spatial extent
- 200-800km diameter
- erratic path
- predictability
- visible from satellite images
- predictable from temperature and weather trends
- erratic path (not more than 12 hour advance notice- since the path of hurricanes are erratic)
- seasonal and regional
- frequency
- seasonal
- relatively regular
- magitude
- wind speeds
- amount of rainfall
- duration
- depends on wind-speed
- amount of rainfall
- speed of onset
- slow to moderate, depends on wind-speed
- factors affecting damage
- Physical
- distance from coast
2
IB Geography — Option D: Hazards and Disasters
Definition:
Term Definition
Disaster A major hazard event that causes widespread disruption to a community or region that
the affected community is unable to deal with adequately without outside help.
Hazard A threat that has potential to cause loss of life, injury, property damage, socio-economic
disruption or environmental degradation.
Hazard event The occurrence of a hazard, the effects of which change demographic, economic and/or
environmental conditions.
Risk The probability of a hazard event causing harmful consequences (expected losses of in
terms of deaths, injuries, property damage, economy and environment).
Vulnerability The susceptibility of a community to a hazard or to the impacts of a hazard event.
1. Characteristics of hazards
Characteristics
Explain the characteristics and spatial distribution of the following hazards.
• Earthquakes/Volcanoes
- earthquake: sudden, violent shaking of the earth’s surface
- spatial distribution:
- regional
- tsunamis
- focus (beneath ground), epicenter (surface)
- occur in clearly defined linear patterns
- locations generally follow plate boundaries
- predictability:
- temporally largely unpredictable
- spatially predictable
- observing crustal movement of plates (uplift, subsidence, ground tilt)
- change in rock stress or electrical resistivity
- anomalies in magnetic field of earth
- strange and abnormal animal behavior
- historic trends and micro earthquake activity
- hazard zone mapping
- frequency:
- frequent in prone regions
- intervals largely unpredictable
- magnitude
- measured by Richter Scale
- Mercalli Scale
- intensity value to measure earthquake effect
- duration:
- for tens of seconds
- aftershocks last for extended period
- usually the longer the fault the longer the quake
- dependent on type of rock, magnitude, distance from epicenter
- speed of onset
- rapid, immediate
- factors affecting damage
1
, Geography Notes Option D: Hazards and Disasters
- Physical
- strength and depth of earthquake
- number of aftershocks
- time of day
- duration of shaking
- distance from epicenter
- type of rocks and sediments (liquefaction)
- occurrence of secondary hazards
- height above sea-level
- Human
- population density
- type of building
- economic development
- emergency and relief services
- preparedness of people
- dealing with earthquakes
- improving forecasting and warning systems
- improving building design, locations, regulations and quality monitoring
- occur along the boundaries of the tectonic plates that make up the earth’s crust
- can be caused by human activities such as: nuclear testing, building large dams, drilling for oil and coal mining
• Hurricanes/Cyclones/Typhoon
- name:
- hurricanes/tropical storms (Atlantic Ocean)
- typhoons (Pacific Ocean)
- tropical cyclones (Indian Ocean)
- necessary conditions of formation
- tropical depression (intense low-pressure system)
- warm tropical oceans (>26.5’C)
- disturbance in lower atmosphere
- Cariolis force determines direction of rotation of cyclone
- above Tropic of Capricorn, below Tropic of Cancer, away from equator
- temperature over 27 degree celsius to a depth of 60 meters
- low pressure area has to be far enough away from the equator so that the force that caused by the rotation
of the earth creates rotation in the rising air mass
- conditions must be unstable: some tropical low-pressure systems develop into hurricanes, but not all
- spatial extent
- 200-800km diameter
- erratic path
- predictability
- visible from satellite images
- predictable from temperature and weather trends
- erratic path (not more than 12 hour advance notice- since the path of hurricanes are erratic)
- seasonal and regional
- frequency
- seasonal
- relatively regular
- magitude
- wind speeds
- amount of rainfall
- duration
- depends on wind-speed
- amount of rainfall
- speed of onset
- slow to moderate, depends on wind-speed
- factors affecting damage
- Physical
- distance from coast
2
