1

Natural Hazards?

1. A natural disaster (physical event) volcanic eruption Earthquake Landslide

2. Human activity Ex: coastal settlement of

populations2

Basically…..

A natural hazard isa naturally occurring event/phenomenon

that has the ability to have an effect on

people

3

Vulnerability Vulnerability = susceptibility to injury or

attack

Human vulnerability leads to financial, structural, and human losses.

Natural hazards only occur in inhabited areas A natural disaster in an uninhabited area has little

tangible impact on people

Natural hazards are increasing because of… Population growth (more people) Urbanization (lots of people in small spaces) alteration of the natural environment (manmade

islands)

4

Hazards’ Human Costs Every year natural disasters leave…

4,000,000 homeless 46,000 injured 5520 dead

These figures do not include the recent tsunami in Asia (273,000) and Hurricane Katrina (1000)

Source: The International Red Cross

5

So what is a natural disaster?

a naturally occurring event/phenomenon that has had an effect on people

Can you think of any?

6

Can natural disasters have positive effects?

7

Positive Effects natural disasters have beneficial

ecological consequences. rejuvenation of a coniferous forest

months and/or years after fires recharging of groundwater stocks after a

flood).

benefits tend to become apparent months or years after an extreme event

8

Methods of Classification

Calculating human costs Impact measured by:

loss of life (total deaths) number of injuries damage to property (replacement

costs)

9

Methods of Classification

Strength/size/intensity of event Hurricane system

Tropical depression, tropical storm, category 1-5

Tornado scale Force 1-5

Richter scale (seismic events) Scale of 1-9, with 9 being cataclysmic,

worldwide event Epidemic, pandemic

10

Methods of Classification

Regional occurrence Hurricane (Atlantic) Typhoon (Pacific rim) Monsoon (Asia, Africa)

Frequency of occurrence Annually? Centenially?

11

Disaster Categories

We classify natural disasters by the chief process or sphere in which it operates Ex: Atmosphere, biosphere,

lithosphere This system has three

categories

12

Atmospheric Hazards

Cyclonic Storms (hurricane, typhoon, cyclone)

Tornado (twisters, dust devils)Severe Storm (White Juan, Nor’easter)Flooding (heavy rains)Drought (lack of rain, prolonged high

pressure)Wildfire (wind, lightning)Severe Weather (hot/cold) ex: ice

storm13

Biological Hazards

Infectious Disease HIV, H1N1, Bubonic Plague

Parasitic Disease ringworm

Insect Infestation malaria, West Nile virus

14

Geological Hazards

Slide (mud, land, rock)Volcanic ActivityEarthquakeAvalancheTsunami (tidal wave)

15

Comparison and Analysis

Any one disaster can be described by analyzing various factors that determine how great an impact it will have on people

This system recognizes six main factors

16

Comparison and Analysis

1. Frequency how often is the event likely to

happen

2. Duration the length of time the event lasts

3. Extent Size of area or region affected

Town? Continent? Region?

17

Comparison and Analysis

4. Speed of onset4. sudden, without warning, over quickly?5. build slowly before a peak period

5. Spatial dispersion area likely to be affected by a particular

event

6. Temporal spacing how hazards and disasters occur in time;

are they random or do they occur within a cycle

18