3.3 hazard assesment

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Hazard Assessment

Hazard assessment is the basic step in community risk

assessment. Hazard assessment helps us to identify thethreats and understand their nature and behavior.

What is A Hazard?

A potentially damaging physical event, phenomenon and/or

human activity, which may cause the loss of life or injury,

property damage, social and economic disruption or

environmental degradation (UNISDR, 2004).

Popular Classification

Natural

Combination

Human Induced


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Hazard

There is a potential for

occurrence of an event


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Hazard Assessment

"The process of studying the nature of hazards determining

its essential features (degree of severity, duration, extent,

impact on the area) and their relationship".

Some Important Points to Consider in Hazard Assessment

o Look at scientific and statistical data

o Historical record

o Approach other knowledgeable sources/people

o Understand the various intensities of the same hazard

o Hazard mapping


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Possible Reasons for New Hazards

Natural - changes in the pattern of weather leading to new

forms of drought and flooding.

Economic - Fluctuations in the value of currency affecting

livelihoods, trade related policy changes.

Social and political trends- Changes in policies, Re-

locations of people, Conflicts.

Industrial hazards- chemical accidents, poisoning.

New forms of epidemics- Bird Flu, AIDS, Hepatitis B & C

Factors to Consider in Understanding the Nature &Behavior of Hazards

01. One Hazard Causing a Secondary Hazard

In case of Earthquake, which can bring furtherhazards like

Building collapse

Dam failureFire

Hazardous material spill Interruption of power/water supply/communication/transportation/ waste disposal

Landslide

Soil liquefaction

Tsunami


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Flood: Epidemics, snake bite, dam Failure

Drought: Epidemics, Famine

Civil war: Refugees & Displaced persons

Landslide: Epidemics, Temporary damming

Pollution: Diseases


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2. Origin: The factor/s which create or result in a hazard. Disastersexperienced in the past.

3. Force which can damage:

The power of the hazard e.g. intensity of the cyclone;

magnitude of the earthquake; wind, water (rain, flood,

overflow, flash flood , epidemic) land (slides, deposits by river,

mudflow) fire (forest fire, settlement fire), seismic (earthquake,

tsunami, liquefaction), conflicts (civil war, insurgency, other

actions leading to displacement and refugees),

industrial/technological (pollution, radio-activity, explosions),

others.

4. Speed of onset:

Rapidity of arrival and impact (rapid and slow-onset). We can

distinguish between hazards that occur without almost any

warning (earthquake), and hazards that can be predicted 3 to 4

days in advance (cyclone) to very slow-onset hazards like drought

and famine.

5. Frequency:

How often does hazard occur -seasonally, yearly, once every 10

years, once in a lifetime, etc.


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6. Forewarning: time gap between warning signs and impact

7. Warning signs and signals:Rainfall duration, intensity, quantity, speed of wind,temperature, movement of animals, insects and birds etc. incase of floods.

8. Period of Occurrence or When :

Does hazard occur at a particular time of the year (wet or dryseason; in November to December)

9. Duration:

How long is hazard felt (earthquake and aftershocks;days/week/months that area is flooded; length of period ofmilitary operations)

QuantitativeQuantitative ApproachApproach

Use mathematical functions with numerical values

Each variable will describe the relationship among parameters that

characterize the phenomena

Assessment ApproachesAssessment Approaches


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Example of Quantitative ApproachExample of Quantitative Approach

Table

No

02

Hazard

Assesm-

ent


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Required Data

Some Quantitative or Spatial Hazard Data in Various Forms

Geological hazard maps showing fault lines or unstable slopes

liable to cause landslides

Hydrological maps of flood-prone areas

Wind, rainfall and sea-surface temperature data

Recording of seismic activity from monitoring stations

Local rainfall and flood level records

Qualitative ApproachQualitative Approach

Use qualitative descriptions (such as low,

medium or high) instead of numerical values

Hazard Assessment Matrix

Hazard map

Seasonal calendar

Historical profile


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Hazard Matrix or Table

Hazard

Type

Origin/

Cause Warning

Signs

Fore-

warning

Force

Speed of

Onset

Frequency

Period of

Occurrenc

e(When)

Duration

Flood

1.Torrential

RF

2. Seasonal

Rainfall

3. Storm

4. Dam

Burst

5 days

continuou

s heavy

rain ,

movemen

t of ants

Relatively

short but

can vary

from a few

hours (over-

night) to a

few days

Volume

of water

Can

often be

predic-

ted a

few days

in

advance

Once or 2

times/

year

Monsoon

season

7 days

Hazard Map


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Ranking

Seasonal Calendar


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1

Seasonal Calendar

Historical Profile


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Hazard Assessment Modeling

Some Guidelines in Hazard Assessment Look at scientific and statistical data

Country Disaster Profile,

EM-DAT: www.em-dat.net

Take action to translate scientific data into practical information

Integrate local knowledge with scientific and technical information

Approach knowledgeable sources/people

Understand the various intensities of the same hazard
http://www.em-dat.net/http://www.em-dat.net/http://www.em-dat.net/http://www.em-dat.net/


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Look out for secondary hazards

Focus on new or emerging hazards

Be aware of local threats: the increasing number of

small scale, localized hazards which do not hit theheadlines or appear in disaster statistics. Cumulatively,these can present a more serious problem than acatastrophic event. For example, in densely populatedshanty towns, regular fires, floods, landslides, andepidemics are increasingly common events.

Bring available maps to facilitate drawing of hazardmaps

Specifying the nature and behavior of the hazard isspecifically important in designing early warningsystem, especially at the local and community


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Scoring Assistance for Table No 021. Likelihood Of Event.

a. None. A disaster event is not likely to occur.

b. Rare. A disaster event occurs less often thanonce every 30 years (e.g. once every 50 years).

c. Occasional. A disaster event occurs less often thanonce every 5 years, but more often than once

every 30 years (e.g., once every 12 years).

d. Frequent. A disaster event occurs more often thanonce every 5 years (e.g., once every 2 years).

2. Impact On Population.a. No Impact (0). No impact means that there is little

or no likelihood of this hazard affecting the

community or, if it occurs, there would be a minimal

affect on the Medical Center.

b. Limited (1). Limited impact means that a disaster

occurrence generally involves a serious threat to a

moderate number of people in the community.There may be a few deaths and injuries and only

minor population dislocations from such an

occurrence (e.g., a typical avalanche or landslide).


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c. Substantial (2). Substantial impact means that a

disaster occurrence affects a significant number of

people, and may involve some loss of life, injuries

and possibly a sizable dislocation of population.Some occurrences of transportation accidents,

urban fires, and floods fall into this category.

d. Major (3). Major impact means a disaster

occurrence affects a widespread area of the

community or a concentrated area with severe

effects. It may result in a large number of deaths

and injuries and involve a massive evacuation

and/or shelter operation. Large-scale earthquakes,

tornadoes, heavy flooding, and hurricanes fall into

this cate or .

3. Impact On Property.

a. No Impact (0). No impact means there is little or no likelihood ofthis hazard affecting the community or, if it occurs, damage topublic and private property would be minimal.

b. Limited (1). Limited impact means that a disaster occurrencegenerally involves only light damage to public or private property.Local resources would be adequate to repair or replace thedamaged property.

c. Substantial (2). Substantial impact means that a disaster

occurrence results in moderate damage over a widespread orconcentrated area. Damage to public and private property mayexceed local resources to Repair or replace.

d. Major (3). Major impact means that a disaster occurrence resultsin heavy damage to public and private property over a widespreadarea or a concentrated area with severe effects. The magnitude ofthe disaster may result in a Government Declaration of a MajorDisaster or Emergency .

3.3 hazard assesment

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