What Determines the Severity of a Hazard? Flashcards
Duration.
Length of time the hazard lasts for.
Longer the hazard more severe it will be.
Magnitude.
Strength of hazard.
Most hazards measured on a scale.
eg richter scale or the volcanic explosivity index.
Stronger hazard the more severe the hazard is.
Predictability.
Some hazards are easier to predict than others.
eg volcanoes normally give warning signs before they erupt.
However, others like earthquakes much harder to predict.
Hazards that hit with no warning are going to be more serious.
Regularity.
If hazards happen often and in quick session eg earthquake followed by multiple aftershocks then the severity is likely to be greater.
During hurricane season countries can be hit by repeated storms each causing great damage as unable to recover from previous damage.
Frequency.
The return interval of hazards of certain sizes.
eg earthquakes with magnitude of 8.0 happen on average once a year but earthquakes of only 3/4 happen many times a day.
If the hazard is a less frequent strong event then its going to have bigger impact.
Speed of onset.
If the peak of the hazard arrives first or arrives quickly eg earthquake then the effects are likely to be worse than one that arrives slowly.
Spatial Concentration.
Where hazards are located or centred.
eg earthquakes tended to be focused along plate boundaries, whereas tropical storms tend to be located in coastal areas in tropics
Hazards located in known areas can be better prepared.
Areal extent.
If hazard covers a large area.
eg drought covering whole of eastern Africa, then severity of hazard is likely to be more severe, than a flood hitting just one village.
Number of hazards.
If location it hit by multiple hazards that the affects can be more severe.
eg hazard hotspots like Indonesia can be hit by earthquakes, volcanoes, landslides and flooding all simultaneously.
What happens when the magnitude of a hazard increases…
The frequency of the hazard happening actually decreases.
