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IHRC
Hurricane Hazards Pamphlet
Wind Damage
Rainfall and Flooding
Storm Surge
Beach Erosion
Tornadoes
Wind Damage
Hurricanes are categorized by sustained wind speeds using the Saffir-Simpson
Hurricane Scale. To date there have only been three category 5 hurricanes
to affect the United States (Labor Day Hurricane of 1935, Camille
of 1969, and Andrew of 1992). When Hurricane Andrew struck in 1992,
it destroyed or damaged 80,000 buildings. Property damage exceeded
$30 billion, making Andrew the costliest U.S. natural disaster.
Hurricane Andrew. Close-up of 1 x 4 board driven through the
trunk of a royal palm (NOAA)
Rainfall and
Flooding
Flooding from heavy rains can be the most devastating aspect of
hurricanes. According to recent findings by the National Hurricane
Center, 81 percent of deaths directly related to tropical cyclones
between 1970 and 1998 were the result of drowning; 71 percent of
these deaths occurred due in fresh water. Minimal strength storms
can cause a major hazard due to flooding as illustrated by Hurricane
Irene, more than 18 inches of rain fell in parts of South Florida.
This contributed to the deaths of 8 Florida residents and caused
$800 million in water damage. Flooded roadways made it impossible
for residents to escape, leaving entire communities cut off by flooded
waters. Over 30,000 families were displaced and 50 people died as
Tropical Storm Allison swamped 70 counties and 50 states. Losses
due to water damage exceeded $6 billion.
Flooding along the Texas coast following passage of Hurricane
Beulah (NOAA)
Storm Surge
Storm surge is a rapid rise of sea level that occurs as a hurricane
approaches a coastline. The most destructive effects of a storm
surge are felt on beaches, offshore islands and low-lying coastlines.
According to 2000 U.S. Census data, during the last ten years coastal
populations have risen 20 percent in the states most vulnerable
to hurricanes. More than 11 million people could be affected by
storm surge flooding. Hurricane Camille (1969) produced the highest
recorded surge, reaching nearly 25 feet at Pass Christian, Mississippi.
During the 1900 Galveston, Texas Hurricane, 6,000 people were swept
away to their deaths due to storm surge, making this storm the deadliest
natural disaster in United Stated History.
Storm Surge (NWS)
Graphic by Robert Simmon (NASA GSFC)
Beach Erosion
For many coastal states-especially in Florida- beaches are essential
to tourism. Erosion caused by a single storm can result in drastic
loss of beach width. For instance, Hurricane Michelle (2001) contributed
to the most severe beach erosion experienced at Hollywood Beach,
Florida in two decades. After a week of pounding surf, some beaches
in the area became critically narrow.
Beach Erosion (Stephen Leatherman)
Tornadoes
Many Hurricanes bring tornadoes with them, adding to their destructive
power. Tornadoes are usually found around the center of the hurricane
where the thunderstorms occur. Tornadoes comprise tight circulating
winds moving at a Fujita speed of F1 and F2 with a forward motion
speed reaching 30mph.
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F-Scale Number
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Intensity Phrase
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Wind Speed
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Type of Damage Done
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F0
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Gale tornado
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40-72 mph
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Some damage to chimneys; breaks branches off trees;
pushes over shallow-rooted trees; damages sign boards. |
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F1
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Moderate tornado
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73-112 mph
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The lower limit is the beginning of hurricane
wind speed; peels surface off roofs; mobile homes pushed off
foundations or overturned; moving autos pushed off the roads;
attached garages may be destroyed. |
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F2
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Significant tornado
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113-157 mph
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Considerable damage. Roofs torn off frame houses;
mobile homes demolished; boxcars pushed over; large trees snapped
or uprooted; light object missiles generated. |
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F3
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Severe tornado
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158-206 mph
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Roof and some walls torn off well constructed
houses; trains overturned; most trees in fores uprooted |
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F4
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Devastating tornado
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207-260 mph
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Well-constructed houses leveled; structures with
weak foundations blown off some distance; cars thrown and large
missiles generated. |
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F5
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Incredible tornado
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261-318 mph
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Strong frame houses lifted off foundations and
carried considerable distances to disintegrate; automobile sized
missiles fly through the air in excess of 100 meters; trees
debarked; steel re-inforced concrete structures badly damaged. |
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F6
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Inconceivable tornado
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319-379 mph
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These winds are very unlikely. The small area
of damage they might produce would probably not be recognizable
along with the mess produced by F4 and F5 wind that would surround
the F6 winds. Missiles, such as cars and refrigerators would
do serious secondary damage that could not be directly identified
as F6 damage. If this level is ever achieved, evidence for it
might only be found in some manner of ground swirl pattern,
for it may never be identifiable through engineering studies |
A waterspout off the Florida Keys photographed from an aircraft
(NOAA, Joseph Golden)
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