Transcript Chapter 2

Chapter 2
Natural and Technological Hazards
and Risk Assessment
4th Edition - 2011
Key Definitions
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Hazard: as a “source of danger that may or may
not lead to an emergency or disaster and is named
after the emergency/disaster that could be so
precipitated.”
Risk: the interaction of a hazard likelihood and
the consequences should it occur
Emergency Event: one that requires the efforts of
one or more of the emergency services to manage
Disaster: an emergency event that exceeds the
capacity of emergency services in one or more
critical areas
Natural Hazards
Exist in the natural environment and
pose a threat to human populations
and communities.
 Exacerbated by human development
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Floods
Can be slow or fast rising
 Many causes, including large-scale weather
systems, thunderstorms, snowmelt, ice
jams, and dam failures
 The most frequent and widespread disaster
in many countries around the world
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Earthquakes
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A sudden, rapid shaking of the earth caused by the
breaking and shifting of rock beneath the earth’s
surface
Active seismic zones have been identified around
the globe – millions exposed
Difficult to predict
Often cause secondary disasters, such as fires,
landslides, avalanches, tsunamis, or dam failures,
among others.
Measured by the Richter Scale or Modified
Mercalli Intensity Scale
Hurricanes
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Tropical wave → tropical depression → tropical storm
→ hurricane
Hurricane must have sustained winds greater than 74
mph.
Storm surge, rains, and high winds cause damage
US hurricane season – June 1 to November 30
Described using the Saffir-Simpson Scale
Hurricane tracking has advanced rapidly
Hurricane Katrina the most costly disaster in US
history
Storm Surges
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Dramatic rises in sea level and large coastal waves
that cause flooding and erosion
Most common from late fall to early spring but
can develop year-round
Usually associated with extra-tropical cyclones
(nor’easters) in the North Atlantic Ocean and the
Gulf of Mexico, and severe winter low-pressure
systems in the North Pacific Ocean and the Gulf
of Alaska
Katrina storm surge reached 28 feet, devastated
the Gulf Coast
Modeled using SLOSH
Tornadoes
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Rapidly rotating vortex or funnel of air extending
groundward from a cumulonimbus cloud
Approximately 1,200 tornadoes are spawned by
thunderstorms each year
Can lift and move huge objects, destroy or move
buildings, and siphon water
People living in valleys have the greatest exposure
Tornado Alley: TX, OK, AR, MO, and KS.
Measured by the Enhanced Fujita-Pearson Scale
Safe rooms are the greatest defense
Wildfires
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Surface fire: most common; burns along forest floor;
moves slowly and kills or damages trees;
Ground fire: usually started by lightning; burns on or
below the forest floor
Crown fire: spreads rapidly by wind and moves
quickly by jumping along the tops of trees
Risk increases as people move into the wildland-urban
interface
Severe drought and fuel buildup have led to a
significant increase in US wildfires
Mass Movement Hazards
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Horizontal or lateral movement of large quantities
of physical matter
Most prevalent in rugged/varied topography
Can include:
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Landslides
Mudflows
Lateral Spreads
Rock Falls
Avalanches
Land Subsidence
Expansive Soils
Tsunamis
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A series of waves generated by an undersea
disturbance such as an earthquake, landslide, or
volcanic eruption
Travel from area of disturbance at high speeds, across
long distances
Waves slow down and rise when they approach the
shoreline, reaching heights of up to 100 feet
Most deaths are caused by drowning
The 2004 Indian Ocean tsunami killed between
150,000 and 200,000 people in 11 countries
Volcanoes
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A break in the earth’s crust from which molten
rock (magma) exits onto the surface
When pressure from gases and magma increases,
eruptions occur
Lava, gas, rock, may spread over large areas
Volcanic ash may travel hundreds of miles, can
contaminate water, cause electrical storms, and
collapse roofs
An erupting volcano can trigger tsunamis, flash
floods, earthquakes, rock falls, and mudflows,
among other secondary hazards
Severe Winter Storms
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Consist of extreme cold and heavy snow or ice
A blizzard combines heavy snowfall, high winds,
extreme cold, and ice
In the US, the weather patterns are from four
sources:
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The North Pacific Ocean or the Aleutian Islands
Canadian and Arctic cold fronts
The Great Lakes
The Atlantic Ocean and Gulf of Mexico
In 2006, the Federal Government began measuring
Severe Winter Storms using NESIS
Drought
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A prolonged shortage of available water caused by a deficiency
of rainfall or because of exceptionally high temperatures and
low humidity
Drought differs from other hazards in three ways:
– The onset and end are difficult to determine because the
effects accumulate slowly and may linger even after the
apparent termination of an episode
– The absence of a precise and universally accepted definition
adds to the confusion about whether a drought exists, and if
it does, the degree of severity; and
– Drought effects are less obvious and spread over a larger
geographic area.
Extreme Temperatures
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Major diversions from average seasonal
temperatures
Can cause injuries, fatalities, and major economic
impacts when prolonged or coincide with other
disaster events
Extreme Heat - 10 degrees or more above regional
averages lasting for several days or weeks
Extreme Cold – no accepted ‘standard’, but occur
when temperatures fall far below averages for an
extended time
Coastal Erosion
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Measured as the rate of change in the position or
horizontal displacement of a shoreline over a
period of time
Generally is associated with storm surges,
hurricanes, windstorms, and flooding hazards
May be exacerbated by human activities such as
boat wakes, shoreline hardening, and dredging
Thunderstorms
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Heavy rainstorms that may be accompanied by
strong winds, hail, lightning, tornadoes.
Generated when the following exist:
– Unstable warm air rising rapidly into the atmosphere;
– Sufficient moisture to form clouds and rain;
– Upward lift of air currents caused by colliding weather
fronts (cold and warm), sea breezes, or mountains
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May occur singly, or in clusters
Hailstorms
An outgrowth of a severe thunderstorm
 Balls or lumps of ice greater than 0.75 inch
 Occur more frequently during late spring
and early summer
 Cause nearly $1 billion in property and crop
damage annually.
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Technological Hazards
Exist because of human innovation and
activity
 Newer and less understood than natural
hazards
 Include hazards that are non-intentional,
such as transportation accidents, and
intentional, such as terrorism.
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Structural Fires
Can be triggered or exacerbated by
lightning, high winds, earthquakes,
volcanoes,and floods
 Lightning is the most significant natural
contributor to fires affecting the built
environment
 Buildings with rooftop storage tanks for
flammable liquids are particularly
susceptible
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Dam Failure
Potentially the worst flood event
 Usually the result of neglect, poor design, or
structural damage caused by a major event
such as an earthquake
 When a dam fails, a gigantic quantity of
water is suddenly let loose downstream,
destroying anything in its path
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Hazardous Materials Incidents
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Chemical substances, if released or misused, can
pose a threat to the environment or health
HazMats may be explosive, corrosive, flammable,
poisonous, and/or radioactive
Most often released because of transportation,
manufacturing, or storage accidents
May cause death, serious injury, long-lasting
health effects, and damage to buildings, homes,
and other property
Nuclear Accidents
Exposure to radiation is the main hazard
 Exposure could come from plant material
release
 Area affected determined by amount
released, wind direction and speed, and
weather
 On-site ERPs approved by the NRC - Offsite plans evaluated by FEMA
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Terrorism
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The use of force or violence against persons or
property in violation of the criminal laws of the
United States for purposes of intimidation,
coercion, or ransom
Before 9/11, most US terrorism involved bombs
Effects vary death/injury to property damage and
service disruption
Governments reduce vulnerability by increasing
security
Terrorism may be domestic or international
CBRN Incidents
Family of weapons characterized by their
broad-sweeping intended effects, such as
inflicting mass casualties and/or physical
destruction
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Chemical
Biological
Nuclear
Radiological
Chemical Weapons
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Naturally-occurring or manmade liquids, gases, or solids
(typically in the form of dust)
Toxic effects on humans, animals, plants, or property
Must be delivered onto or around intended victims to be
effective
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Aerosolized
Dropped
Splashed
Poured
Released by bombs
Sprayed from containers or vehicles
Detection a challenge
Biological Weapons
Organisms or toxins either naturally
occurring or genetically engineered, that
can kill or incapacitate people, livestock,
and crops
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– Bacteria
– Viruses
– Toxins
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Most are difficult to grow and maintain
Radiological Weapons
Commonly referred to as a “dirty bomb” or
“radiological dispersion device (RDD)”
 Use common explosives to spread
radioactive materials over a targeted area
 Distinct from nuclear blasts (much more
localized)
 Presence of radiation may not be
recognized, will be harmful to those
exposed, and may be very difficult to
remove or contain
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Nuclear Weapons
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Cause great harm through the activation of a fission or
fusion chain reaction
Possible only through the advanced technology and using
only the most refined nuclear materials
Explosion emits intense light and heat, damaging pressure,
and disperses radioactive debris over a widespread area
leading to the contamination of air, water, and ground
surfaces for miles around.
The likelihood of a terrorist organization developing an
operational nuclear weapon is almost nil
A successful use of a nuclear weapon would cause
thousands of deaths and destroy billions in property
Hazards Risk Management
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Process by which individuals, communities, and
countries deal with the hazard risks they face
A primary function of government
Many different methodologies exist
A four-step process that includes:
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Identifying the hazards
Assessing risk for each hazard identified
Analyzing hazard risks in relation to each other
Treating hazard risk according to prioritization
Hazard Identification
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All hazards that have or could affect an area of
focus are identified and described
Done through:
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Historical study
Brainstorming
Scientific analysis
Subject matter expertise
For more common hazards the presence of the
hazard will be obvious
For new or changing hazards the knowledge or
opinion of experts is required
Hazard profiling a key component
Hazard Risk Assessment
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The threat posed by each hazard is investigated
Risk calculated according to two equal factors:
– Hazard likelihood
– Hazard consequence
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These factors inform us of how concerned we
should be about the existence of a hazard, and
what we can do to prevent or treat the hazard
Generally, high likelihood / high consequence
hazards are of greatest concern
Can be qualitative or quantitative
Hazard Risk Analysis
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Determines the relative seriousness of hazard risks
that have been identified and assessed
Most communities have a range of competing
budgetary pressures and are therefore unable to
fully mitigate all hazard risk
Commonly conducted through a risk matrix
– A graph that represents risk likelihood and consequence
on the X and Y axes
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Vulnerability analysis can help to determine what
is causing risks, why certain risks rank above
others, and what can be done to increase resilience
or decrease vulnerability through the various risk
treatments
Hazard Risk Treatment
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Reduction in either the likelihood or impacts of a
hazard
Hazard risks are treated through hazard mitigation
and disaster preparedness
Risk treatment option selection takes the risk
assessment methodology beyond process to
decision-making and action
Analysis of cost effectiveness, acceptability by
society, and long term positive and negative
impacts
Process technical / political
Risk Management Technology
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In the last 15 years, technological advances have
refined the ability to identify and understand the
nature of hazards and develop better risk
assessment methods
Recent technological advances include:
– satellite and aerial imagery and radar to map
floodplains and coastal erosions
– loss estimation from various earthquake scenarios
– safe rooms for homes in tornado-prone areas
Social and Economic Risk Factors
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Strong correlation between disasters and poverty
Risk assessments consider populations homogeneous
Social advocacy work to raise vulnerability awareness
of ‘special populations’
Katrina revealed the socioeconomic vulnerability
divide
The social makeup of a population is based upon a
diverse set of factors that includes education, culture,
local government, social interaction, values, laws,
beliefs, and other aspects of society