DISASTER SCENARIOS
A PRIMER OF KNOWLEDGE THAT
CAN MULTIPLY AND SPILL OVER FOR
THE BENEFIT OF MILLIONS
Walter Hays, Global Alliance for
Disaster Reduction, University of
North Carolina, USA
DISASTER SCENARIOS
FOR SEVERE
WINDSTORMS
HURRICANES, TYPHOONS, AND
CYCLONES
SEVERE WINDSTORMS:
HURRICANES
• In the Atlantic, Caribbean, Gulf
of Mexico, and Eastern Pacific
areas cyclonic tropical storms
with well-formed central “eyes”
and with wind speeds above 74
mph are referred to as
HURRICANES.
SEVERE WINDSTORMS:
TYPHOONS
• The exact same phenomenon
in the Western Pacific Ocean
region is called a TYPHOON.
Physics Of A Typhoon
SEVERE WINDSTORMS:
CYCLONES
• The exact same phenomenon in
the Indian Ocean region is
called a CYCLONE.
SEVERE WINDSTORMS:
TYPHOONS OR CYCLONES
• People in South East Asia
occasionally refer to severe
windstorms as either
TYPHOONS or CYCLONES.
SEVERE WINDSTORMS:
NOR’EASTERS
• People on the USA’s and
Canada’s eastern seaboard
and Northern Europe
occasionally experience
severe windstorms known as
NOR’EASTERS.
DEVELOPING A REALISTIC
DISASTER SCENARIO FOR
A COMMUNITY FACING
SEVERE WINDSTORMS
A POLICY FRAMEWORK
RISK ASSESSMENT
• VULNERABILITY
SEVERE
WINDSTORMS
• COST
• EXPOSURE
• EVENT
EXPECTED
LOSS
• BENEFIT
•CONSEQUENCES
POLICY ASSESSMENT
POLICY
ADOPTION
THE KEYS:
1) KNOW YOUR REGION’S
METEOROLOGICAL
HISTORY,
2) KNOW YOUR
COMMUNITY
1325 HURRICANE PATHS: 1851-2004
• EACH HURRICANE
HAS PREDICTABLE
PHYSICAL
CHARACTERISTICS
THAT CAN BE USED
TO DEVELOP
DISASTER
SCENARIOS WITHIN
A REALISTIC POLICY
FRAMEWORK.
HURRICANE BILL’S PATH: AUGUST
12-24, 2009
• THE PATH IS A
STARTING
POINT FOR
ANY DISASTER
SCENARIO FOR
HURRICANES
OR TYPHOONS.
TYPHOON MORAKOT’S PATH:
AUGUST 3-10, 2009
• THE STATE- OFPREPAREDNESS
OF COMMUNITIES LOCATED
IN THE LANDFALL AREA
DEFINES THE
POSSIBILITY OF
DISASTER.
FACTORS THAT ENHANCE
DESTRUCTIVENESS
• Very low pressure in the “eye”
(increases the height of storm
surge and likelihood that wind
will lift roofs off buildings and
pop out windows after landfall)
FACTORS THAT ENHANCE
DESTRUCTIVENESS
• Low vertical wind shear along
the path of the storm
(maintains storm’s
cohesiveness and rotation)
FACTORS THAT ENHANCE
DESTRUCTIVENESS
• A long path passing through
warm water and a slow rate of
travel (increases the likelihood
that the storm will grow in
strength and become a
RAINMAKER after landfall)
FACTORS THAT ENHANCE
DESTRUCTIVENESS
• Wind field and rain bands
extending 500 km or more from
the “eye” (increases area of
potential wind damage,
flooding, landslides, and need
for evacuation).
HURRICANE DEAN: PREPARING FOR
EVACUATION, AUGUST 19, 2007
FACTORS THAT ENHANCE
DESTRUCTIVENESS
• Landfall in rain-saturated areas
having steep slopes (increases
likelihood of landslides
(mudflows))
TYPHOON MORAKOT:
TAIWAN
FACTORS THAT ENHANCE
DESTRUCTIVENESS
• Landfall in populated areas that
are unprepared:
• increases the likelihood of inadequate
warning, inadequate evacuation,
inadequate wind engineering (e.g., roof
systems, “safe rooms”), inadequate
safe havens, and inadequate
INSURANCE.
RISK ASSESSMENT FOR
HURRICANES, TYPHOONS,
AND CYCLONES
A RISK ASSESSMENT
• A risk assessment involves the
probabilistic integration of:
• The hazard (e.g., severe
windstorms) and their potential
disaster agents (winds, storm
surge, etc) that are directly related
to the location of the community
and the path/size of the storm.
ELEMENTS OF A SCENARIO
HAZARDS
EXPOSURE
RISK
VULNERABILITY
LOCATION
HAZARDS OF A SEVERE WINDSTORM
(AKA POTENTIAL DISASTER AGENTS)
• WIND FIELD (COUNTER CLOCKWISE
OR CLOCKWISE DIRECTION; CAT 1 (55
mph) TO CAT 5 (155 mph or greater)
• STORM SURGE
• RAIN BANDS OF HEAVY PRECIPITATION
• LANDSLIDES (MUDFLOWS)
• COSTAL EROSION
• POSSIBILILITY OF TORNADOES
An element’s vulnerability
(fragility) is the result of a
community’s actions or
nature’s actions that change the
destructiveness of the storm
MANKIND’S CONTRIBUTION
An element’s vulnerability
(fragility) is the result of flaws
that enter during the planning,
siting, design, and construction
of a community’s buildings and
infrastructure.
TYPHOON MORAKOT:
TAIWAN
TYPHOON MORAKOT:
TAIWAN
MANKIND’S ACTIONS THAT INCREASE
VULNERABILITY
• Urban development or
industrial development along
coastlines prone to severe
windstorms that generate
storm surges, high-velocity
wind, and heavy precipitation.
TYPHOON MORAKOT: CHINA
MANKIND’S ACTIONS THAT INCREASE
VULNERABILITY
• A community locating its
dwellings, schools, hospitals,
etc., and infrastructure in areas
susceptible to storm surge,
flooding, and high winds.
TYPHOON MORAKOT:
TAIWAN
TYPHOON MORAKOT:
TAIWAN
TYPHOON MORAKOT: CHINA
NATURE’S CONTRIBUTIONS THAT
INCREASE VULNERABILITY
• Warm ocean water (creates the
low pressure zone for the “eye”
of the storm)
• Warm ocean water along the
path of the storm (keeps the
storm energized and increases
the wind field strength)
NATURES CONTRIBUTIONS THAT
INCREASE VULNERABILITY
• Low vertical wind shear (keeps
the storm organized)
• Stalled weather systems
(prolongs rain fall, especially
after landfall).
CAUSES
OF
DAMAGE
WIND PENETRATING
BUILDING ENVELOPE
UPLIFT OF ROOF SYSTEM
FLYING DEBRIS
SEVERE
WINDSTORMS
“DISASTER
LABORATORIES”
STORM SURGE
IRREGULARITIES IN
ELEVATION AND PLAN
SITING PROBLEMS
FLOODING AND LANDSLIDES
DISASTER RISK
REDUCTION
RISK ASSESSMENT
•SEVERE
WINDSTORMS
•INVENTORY
•VULNERABILITY
•LOCATION
ACCEPTABLE RISK
RISK
UNACCEPTABLE RISK
SEVERE WINDSTORM
RISK REDUCTION
DATA BASES
AND INFORMATION
Storm Hazards:
Gradient Wind
Wind profile
Ocean
COMMUNITY
-Wind pressure
-Surge
-Rain
-Flood
-Waves
-Salt water
-Missiles
-Tornadoes
POLICY OPTIONS
•PREVENTION/MITIGATION
•PREPAREDNESS
•EMERGENCY RESPONSE
•RECOVERY and
RECONSTRUCTION
• EDUCATIONAL SURGES
EMERGING TECHNOLOGIES FOR
SEVERE WINDSTORMS
• REAL TIME
FORECASTS OF PATH
AND PHYSICAL
EFFECTS
• MEASUREMENT
TECHNOLOGIES (E.G.,
DOPPLER RADAR,
WIND SPEEDS;
PRESSURE,
INTERNATIONAL
SPACE STATION)
• METEOROLOGICAL
HISTORIES
• WIND ENGINEERING
• STORM SURGE MAPS
• STORM CHASER
PLANES/DRONES
• WARNING SYSTEMS
• RISK MODELING (E.G.,
HAZUS, INSURANCE
UNDERWRITING)
SAVING LIVES
WIND ENGINEERING
“SAFE ROOMS”
EVACUATION
TYPHOON MORAKOT:
TAIWAN
TOWARDS DISASTER RISK
REDUCTION FOR SEVERE
WINDSTORMS
RISK ASSESSMENT
• VULNERABILITY
SEVERE
WIND
STORMS
• COST
• EXPOSURE
• EVENT
EXPECTED
LOSS
• BENEFIT
•CONSEQUENCES
POLICY ASSESSMENT
POLICY
ADOPTION