CATASTROPHIC EVENTS
FLOODING Flood any relatively high stream flow overtopping the natural or artificial banks in a water system. Common Causes: Long-lasting rainfall over a broad area Locally intense thunderstorm - generated rainfall Rapid 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.
Destruction of riparian habitat Significant erosion can lead to more frequent flooding if not repaired Water pollution Damaged drainage systems release raw sewage Damaged buildings can be a source of toxic materials (e.g. paint, pesticide, gasoline) EFFECTS OF FLOODS
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 EFFECT ON ECOSYSTEMS Trees damaged, stripped, or uprooted Open forest canopies to sunlight Fallen trees offer shelter for small animals Potential destruction of waste storage or treatment facilities or chemical plants
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.
STORM SURGE The storm surge causes sediment to erode and shift. Coastal wetlands and barrier islands take the brunt of the storm surge. Sediment erosion and deposition often affect Oyster beds Coral reefs Sea grass beds http://www.comet.ucar.edu/ns flab/web/hurricane/313.htm
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 3 rd 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
VOLCANO A volcano is a vent in the Earth which allows molten rock (magma) to escape to the surface. When pressure from gases within the magma become too great, an eruption occurs. Once the volcano erupts, the Earth moves to a state of equilibrium until pressure builds again.
DROUGHT A drought is an unusually long period of dry weather that lasts long enough to cause water supply shortages. One dry year is usually not long enough to produce a severe drought. The severity of the drought depends upon the degree of moisture deficiency, the duration and the size of the affected area.
DROUGHT Some areas can become desert when a drought occurs. Other related problems include crop failure, livestock death, increased forest fires and water shortages. http://staffwww.fullcoll.edu/tmorris/elements_of_ecology/images/drought_corn.jpg