Catastrophic Events

Catastrophic Events•What is a Catastrophic Event?•Any event naturally occurring or caused by human action that:•Causes severe damage to the land•Endangers life OR causes loss of life•Speeds up the effects of erosion and deposition

•Also known as natural disasters

Tornadoes• Winter and Early SpringWinter and Early Spring• Develop from Thunderstorms in warm moist air before east-Develop from Thunderstorms in warm moist air before east-

ward moving cold fronts.ward moving cold fronts.• Extreme low pressure creates rotating winds which causes Extreme low pressure creates rotating winds which causes

materials to be sucked up into a forming funnel like a vacuummaterials to be sucked up into a forming funnel like a vacuum• High speed rotating winds often greater than 250 mphHigh speed rotating winds often greater than 250 mph

• Ranked from F-0 Tornado (light damage such as broken tree Ranked from F-0 Tornado (light damage such as broken tree limbs) to F-5 Tornado (total demolition of and area including limbs) to F-5 Tornado (total demolition of and area including concrete sucked up from the ground)concrete sucked up from the ground)

• Can take lives (human and animals) and destroy propertyCan take lives (human and animals) and destroy property• Uproot trees and scour soil off groundUproot trees and scour soil off ground• Loss of vegetation could hinder plant and animal Loss of vegetation could hinder plant and animal interaction interaction • Causes wind erosion to soilCauses wind erosion to soil

DroughtsDroughts Can be caused by interruption of the water cycle through Can be caused by interruption of the water cycle through

lack of rain, water vapor condensing or even mountains lack of rain, water vapor condensing or even mountains preventing moisture from lowering.preventing moisture from lowering.

Can also be caused by diverting too much water for Can also be caused by diverting too much water for irrigation.irrigation.

One year is usually not long enough for severe droughtOne year is usually not long enough for severe drought Dry spells lasting two or more years cause serious problems Dry spells lasting two or more years cause serious problems

with water not being restored.with water not being restored.

Surface and subsurface water will become below normal Surface and subsurface water will become below normal (will affect humans, animals and vegetation)(will affect humans, animals and vegetation)

- crop failures- crop failures - livestock death- livestock death When plants die, soil will erode fasterWhen plants die, soil will erode faster Will increase forest fires, sand storms and water shortages Will increase forest fires, sand storms and water shortages

– the cycle continues– the cycle continues

http://en.wikipedia.org/wiki/Image:Sandstorm.jpg

Wildfires • LightingLighting• Drought conditions with a lot of wind and low humidity (dry Drought conditions with a lot of wind and low humidity (dry

air)air)• Careless handling of fire (campers, cigarettes, arsonists)Careless handling of fire (campers, cigarettes, arsonists)

• Wildfires produce their own winds that are 10 times Wildfires produce their own winds that are 10 times stronger than most windsstronger than most winds

• Fires can be beneficial for maintaining balances in Fires can be beneficial for maintaining balances in ecosystems if properly managed and controlledecosystems if properly managed and controlled

• Can destroy millions of acres of landCan destroy millions of acres of land• When vegetation is burned, area is prone to erosionWhen vegetation is burned, area is prone to erosion• Animals become endangered from habitat destructionAnimals become endangered from habitat destruction• If it sweeps through inhabited areas, huge economic losses If it sweeps through inhabited areas, huge economic losses

can impact humans and even whole communitiescan impact humans and even whole communities• Affects air quality and also water quality.Affects air quality and also water quality.

Flood• Overflowing of water onto a normally dry piece of land.• Intense and long periods o f precipitation (thunderstorms or hurricanes)• Melting snow and ice

• Floods are controlled by a few factors:

- amount of water building up

- how porous the soil is (able to absorb water)

- how much water is already in the soil• Humans have altered the earth by paving it (foundations, roads, parking lots) and paved things aren’t porous which makes what falls, runoff.

• Floods cause loss of life, disease (by contaminated drinking water), property loss or damage, and destruction of soil (erosion) for crops and livestock.

Hurricanes/Typhoons/CyclonesHurricanes/Typhoons/Cyclones• Warm, moist air (above the oceans) rises and cools creating clouds• Air from the ocean surface rushes upward• As wind ruses upward it begins to spiral• This causes a tropical storm with high winds; but when the winds reach

74+ mph, it is labeled a hurricane.

• Hurricane winds blow in a spiral around a calm center called an “eye”• Storms can be up to 400 miles in diameter with eyes 30 miles wide• Hurricanes may last a week or more• Hurricanes in different regions are called different names: - Atlantic Ocean = Hurricane; Pacific Ocean = Typhoon; Indian Ocean = Cyclone• Hurricanes cause other natural disasters like flooding and tornadoes

• Hurricanes uproot trees and also destroy animal life by destroying habitats and defoliating vegetation.

• Because of the high winds, hurricanes deposit sediment upstream in rivers that could upset the river ecosystem, but they can also erode the soil due to water movement or flooding.

• Produce many deaths because of “drowning” in flood waters or storm surge.

Hurricanes

• Terrestrial Ecosystems• Hurricanes wreak havoc on terrestrial ecosystems. • Strong winds, storm surge, flooding and tornadoes all have an impact.• Coastal wetlands and barrier islands take the brunt of the storm surge. • The storm surge causes sediment to erode and shift.• The hurricane floodwater often carries many toxic substances (Heavy metals,

pesticides, ammonia, phosphate, untreated sewage)• These substance can cause degradation of water quality, phytoplankton blooms, a

decrease in dissolved oxygen and harm to many organisms.• Hurricanes have minimal effect on oceanic ecosystems since the

contaminants tend to be flushed out by tidal flows.• Aquatic Ecosystems

• Sediment erosion and deposition often affect oyster beds and coral reefs.• Saltwater intrusion in freshwater lakes and streams causes massive fish kills

and affects the lakeside habitat.

• Vibration of the Earth’s surface that occurs after a release of energy in the crust.

• This release can be from a volcanic eruption, or movements of segments called faults.

• Can also be caused by plate tectonic collisions.

• The Earth’s crust may actually bend as pressure builds and then finally exceeds the strength of the rock. At that point the crust will break and snap into a new position.

• This process will release any pressures resulting in equilibrium for the crust.

• Seismic “waves” are created in from the center and will travel outward at varying speeds. Can be measured on a “Richter” Scale.

• Can open large cracks in the ground (have even been known to make whole bodies of water disappear).

• Can raise, lower or move large pieces of land.

• Earthquakes hurt the environment by causing soil liquefaction, debris slides, fires or even tsunamis if earthquakes occur on the ocean floor.

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