CATASTROPHIC EVENTS
FLOODING

Flood – any relatively high stream flow
overtopping the natural or artificial banks in a
water system.

Common Causes:
 Long-lasting
 Locally
 Rapid
rainfall over a broad area
intense thunderstorm - generated rainfall
melting of large snow pack with or without
accompanying rainfall
FLOODING

A “100 – year flood” is a
flood that has a 1 in 100
chance of reaching a
certain level in a given
year.
Flash floods can occur from heavy rainfall, but
they can ALSO occur without any rain due to
things like large amounts of snow or ice
melting.
Flash floods occur within 6 hours whereas
“normal” floods take a longer time frame to
accumulate water.
WORST TEXAS FLOOD
The Hurricane of 1900 in Galveston, TX was the
worst natural disaster in American History. It
killed nearly 8,000 people, mainly due to storm
surge from the hurricane.
 For comparison: Hurricane Katrina killed
around 1,200 people.
 A storm surge is flooding caused by hurricane
winds pushing the ocean’s water to land

http://www.youtube.com/watch?v=cxAUoXTUtS
8 – Australia clip
 http://www.youtube.com/watch?v=ceym2c18O
QM – Tsunami flooding – Japan 2011

TORNADOES

Tornado – a localized,
violently destructive
windstorm occurring
over land, especially in
the Mid-West U.S. They
normally have a long,
funnel-shaped cloud
extending toward the
ground.
Tornado from April 3, 2012 in Fort
Worth.
TORNADOES
Tornado from April 3, 2012 in Fort
Worth.
HOW:
- When warm, moist air rises and meets cooler, drier
air, a strong front develops. Strong winds from the jet
stream push the horizontal cylindrical vortex down,
making it vertical. When it touches the ground, a
tornado has formed.
TORNADOES
- Tornado strength is
measured by the Enhanced
Fujita Scale (F-Scale)
- About 1,000 tornadoes a
year form in the U.S.
- 2% (or 20) become F4
and F5
WORST TORNADO IN U.S. HISTORY
The “Tri-State Tornado”
On March 18, 1925,
this tornado formed around
1:00pm and stayed touching
down for 3.5 hours! It set
records for both path (219
miles) and speed across
land (73mph) with wind
speeds in excess of
300mph. Close to 1 mile
wide path width. 695 people
died, a record for 1 tornado.
TORNADO EXAMPLES
http://www.youtube.com/watch?v=xPTXqzMVFUA
http://www.youtube.com/watch?v=vwxKFHZigRw
HURRICANES

A hurricane – forms when a giant, spinning rain
– and windstorm that forms over warm ocean
water reaches at least 74 mph.
HURRICANES

As warm water evaporates, the warm, moist air
rises. At the same time, cooler, drier air fills in
below. As this builds strength and rotates you
first get a tropical depression (40 mph), and
then a hurricane when winds reach 74 mph.
HURRICANES: WHERE
Hurricanes most frequently form
in the Pacific, Atlantic, and
Indian Oceans.
 Hurricanes in the Northern
Hemisphere rotate counter
clockwise.


Hurricanes in the Southern
Hemisphere rotate clockwise
due to the Coriolis Effect.
HURRICANES: DAMAGE/DURATION

The Saffir-Simpson
Hurricane Wind
Scale is used to
categorize hurricane
strength.
http://www.nhc.noaa.gov/a
boutsshws.php
animated wind speed
HURRICANES: DAMAGE/DURATION




Hurricanes can usually last a couple of weeks. The
longest recorded hurricane lasted 31 days in 1994!
The deadliest hurricane was in 1970, in Bangladesh,
killing 300,000 people.
About 8,000 people died from the Hurricane in
Galveston in 1900.
Hurricane Katrina was 3rd in number of deaths, killing
about 1,200 people and was, by far, the most expensive
costing $105.8 billion.
VIDEO OF HURRICANES

http://www.youtube.com/watch?v=LLbpKCZgdM – Hurricane Sandy in New Jersey
2012

http://www.youtube.com/watch?v=-JuQDsDJZ-I
– Hurricane Wilma 10-24-2005
EARTHQUAKES
An earthquake is a sudden and violent shaking of
the ground, sometimes causing great destruction,
as a result of movement in the Earth’s crust.
HOW: When the Earth’s tectonic plates collide or
slide against each other, a large amount of energy is
released from built up pressure or friction.

EARTHQUAKES
WHERE:
- 80% of earthquakes on Earth occur on the rim of
the Pacific Ocean, called the “Ring of Fire”.
- Most earthquakes occur near fault lines (where
tectonic plates meet)
EARTHQUAKES: DAMAGE/DURATION

Scientists assign a magnitude to
earthquakes based on the
strength and duration of their
seismic waves.
3 to 5 = minor or light
 5 to 7 = moderate to strong
 7 to 8 = major
 8 or higher = great
There are an estimated 1.3 million
very minor earthquakes a year that
people will most likely not even
notice.
On average, there is only 1
earthquake that is 8 or higher per
year.
They kill around 10,000 people per
year. (usually from building collapse)

WORST OF THE WORST
WORST in U.S. history:
- 1964 Prince William Sound,
Alaska – Magnitude 9.2
- The ground rose about 12 ft in
some areas.
WORST in history:
- Chile, 1960 – Magnitude
9.5
- 1,665 deaths
- Also triggered a tsunami
that hit Hawaii, Japan, and
the Phillipines
VOLCANOES