Natural Hazards
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communication and defence.
What are Natural Hazards
The natural environment is unstable. People have been learning to deal with the
environmental risks and changes produced by the unstable environment. Extreme natural process (flood, earthquake or landslide…..)has the potential to be a natural hazard if it occurs where people live or have their property (buildings or animals…). Natural disaster when it exceeds normal expectations of frequency or involved.
Example:
The Richter Scale
Speed of onset
It refers to the length of time between the first appearance or warning of an event and its peak.
Example:
Slow-onset hazards (drought and soil erosion)
Hபைடு நூலகம்y fever Infestation
Biological
Faunal
Bacterial, viral and protozoal disease Malaria
Foot and mouth disease
Flood Fog Frost Hailstorm Heat wave Lightning strike and fire
Natural environment may be classified into four categories:
Physical: energy, mineral and soil resources; Biotic: forest, fish, animal and other life resources Geomorphic: flat plains and others Locational: good location for transport,
Floods: days or weeks Tornados: minutes or
hours
Frequency
It refers to how often an event of a given magnitude may be expected to re-occur.
‘Return period’: a recurrence interval of 10 years is to say it has in any year a 10% chance of occurring.
Rapid-onset hazards (floods and earthquakes)
Six Indicators – (cont’d)
Duration
It refers to the period of time over which it occurs.
Example:
Droughts: seasons or years
Erosion Expansive soil Landslide Shifting sand Tsunami Volcanic eruption
Weeds Red tide
Infestation Rabbits Locusts Grasshoppers
Temperature inversion
Tornado Tropical Cyclone Windstorm
Natural Hazards
HO Pui-sing
Contents
What are natural hazards Flooding Drought
Natural environment
Natural environment has provided man with useful resources.
Venn Diagram of Natural Hazards
and Natural Disasters
Responding to those hazards, society may seek to modify the natural events system and the human use system of locations, livelihoods, and social organization.
Classification of hazards
Geophysical
Meteorological
Geomorphic
Blizzard and snow
Avalanche – rock
Cold wave Drought
Avalanche – snow Earthquake
Floral Fungal disease
Six Indicators
Magnitude
It is the most important indicator.
Magnitude rate as ‘extreme’ happenings and pose sufficient threats to the human system to be considered natural hazards.
Measuring and analyzing natural hazards
Six indicators to measure and analyze the extreme geophysical events that comprise natural hazards. They are
Magnitude Speed of onset Duration Frequency Areal extent Areal reliability
What are Natural Hazards
The natural environment is unstable. People have been learning to deal with the
environmental risks and changes produced by the unstable environment. Extreme natural process (flood, earthquake or landslide…..)has the potential to be a natural hazard if it occurs where people live or have their property (buildings or animals…). Natural disaster when it exceeds normal expectations of frequency or involved.
Example:
The Richter Scale
Speed of onset
It refers to the length of time between the first appearance or warning of an event and its peak.
Example:
Slow-onset hazards (drought and soil erosion)
Hபைடு நூலகம்y fever Infestation
Biological
Faunal
Bacterial, viral and protozoal disease Malaria
Foot and mouth disease
Flood Fog Frost Hailstorm Heat wave Lightning strike and fire
Natural environment may be classified into four categories:
Physical: energy, mineral and soil resources; Biotic: forest, fish, animal and other life resources Geomorphic: flat plains and others Locational: good location for transport,
Floods: days or weeks Tornados: minutes or
hours
Frequency
It refers to how often an event of a given magnitude may be expected to re-occur.
‘Return period’: a recurrence interval of 10 years is to say it has in any year a 10% chance of occurring.
Rapid-onset hazards (floods and earthquakes)
Six Indicators – (cont’d)
Duration
It refers to the period of time over which it occurs.
Example:
Droughts: seasons or years
Erosion Expansive soil Landslide Shifting sand Tsunami Volcanic eruption
Weeds Red tide
Infestation Rabbits Locusts Grasshoppers
Temperature inversion
Tornado Tropical Cyclone Windstorm
Natural Hazards
HO Pui-sing
Contents
What are natural hazards Flooding Drought
Natural environment
Natural environment has provided man with useful resources.
Venn Diagram of Natural Hazards
and Natural Disasters
Responding to those hazards, society may seek to modify the natural events system and the human use system of locations, livelihoods, and social organization.
Classification of hazards
Geophysical
Meteorological
Geomorphic
Blizzard and snow
Avalanche – rock
Cold wave Drought
Avalanche – snow Earthquake
Floral Fungal disease
Six Indicators
Magnitude
It is the most important indicator.
Magnitude rate as ‘extreme’ happenings and pose sufficient threats to the human system to be considered natural hazards.
Measuring and analyzing natural hazards
Six indicators to measure and analyze the extreme geophysical events that comprise natural hazards. They are
Magnitude Speed of onset Duration Frequency Areal extent Areal reliability