The Effects of 8 Catastrophic Events that Impact Earth

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The Effects of 8 Catastrophic Events that Impact
Earth

• 7th Grade Science
• PGMS

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Student Directions.

• Turn to each corresponding page of flipbook.
• Circle the type of cause for this event.
• Write in Benefits of each event.
• Each Event benefits earth in some way. How?
• Do not write NONE for benefits.
• Write down Safety Ideas for each event.

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VOLCANO
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HOW VOLCANOES FORM

• When pressure from gases within the magma becomes
  too great, an eruption occurs.
• Once the volcano erupts, the Earth moves to a
  state of equilibrium until pressures build again
• Eruptions can be slow and fairly quiet or
  violently explosive.

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VOLCANOMAIN FEATURES

• A volcano is a vent in the Earth which allows
  molten rock (magma) to escape to the surface.

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IMPACT OF VOLCANOS

• New land can be created by volcanoes but there
  can also be great destruction to the environment
  and human habitats.
• Hazards include searing hot, poisonous gases,
  lava and pyroclastic flows, landslides, mudflows,
  earthquakes, increased fire hazard, explosions,
  rockslides, flash flooding, and tsunamis.

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IMPACT OF VOLCANOS

• Volcanic ash is very fine glassy rock fragments.
• It can affect breathing, contaminate water
  supplies, collapse roofs, disrupt machinery, and
  cause jet engines to fail while flying.

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VOLCANO--NEGATIVE EFFECTS

• When a volcano erupts, people may be killed. When
  Mount St. Helens erupted, 57 people died, even
  though the mountain is in an area of low
  population density and there was lots of warning
  about its eruption. Land may be destroyed. In
  Hawaii, the lava flows from Kilauea burns roads,
  houses, fields, crops, and fences. Entire species
  may be eliminated in an area because the eruption
  either killed them or destroyed their habitat.
  The larger species of animals and the forests of
  Mount St. Helens were very badly affected by the
  most recent eruption. Erosion can produce scars
  which continue to grow as more soil is washed
  from the naked land after an eruption kills the
  forests, scrubs, and grasses. The ash and gas may
  cloud the atmosphere so that it is hard to
  breath, and the sunlight cannot get through. In
  1815, a volcano (Tambora) produced so much ash
  and sulfur that it circled the globe. It was
  called the Year Without a Summer, because the
  weather never did warm up that year.  Tourists
  may stay away because they are afraid of another
  eruption or because the natural beauty of the
  area has been damaged. These are all negative
  consequences of a volcanic eruption.

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BENEFITS OF VOLCANOS

• Many peoples around the world continue to live
  near volcanoes because the eruptions produce
  wonderful soil for growing crops. Most of the
  surface of the North American continent itself
  was produced by the eruption of volcanoes over
  millions of years. The atmosphere of the Earth
  got much of its components from the eruption of
  volcanoes. Even tourism can be positively
  affected. Pompeii is a very popular tourist site
  because of the information preserved there by the
  eruption of Vesuvius.  Mount St. Helens has more
  visitors each year now than it did before the
  explosion, despite the destruction to its natural
  beauty.
• Generally in the short time frame, volcanoes are
  destructive however, in the longer frame of
  time, they are a vital and necessary part of the
  Earth as we know it. Without volcanic eruptions,
  the life we know on the Earth today would not
  exist.

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VOLCANOES
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Mount Tambora--
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Crater Lake, Oregon
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DROUGHT
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What is a drought?

• A drought is a lack of precipitation over a long
  period of time, usually a season or more, that
  results in a water shortage causing adverse
  impacts on vegetation, animals and or people

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Where do droughts occur?

• Most occur in hot areas like Texas, California,
  Nevada, Australia, and Mexico.
• In the US, most are likely to occur in the
  Midwest and South because of the heat waves and
  deserts

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Types of Drought

• Meteorological - lack of precipitation
• Agricultural - low soil moisture
• Hydrological - lack of water in
• watersheds,river systems, and reservoirs

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Negative Effects

• Plants may die leaving soil exposed to winds that
  can carry away topsoil
• Animals may dehydrate and die
• People in undeveloped areas may die from
  dehydration
• 55 of crop failures in the US are due to lack of
  water

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• Texas Drought Monitor

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(No Transcript)
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Lake Travis 2007
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Lake Travis, Aug. 2011
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Wildfires
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What is a wildfire?

• A wildfire is an uncontrolled fire.

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How do they start?

• humans cause 90 of wildfires through campfires
  left unattended, burning of debris, discarded
  cigarettes, and arson
• lightning
• accumulation of leaves, twigs, trees and
  underbrush that can heat up and ignite
• arson (intentional setting of a fire )

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Wildfire Facts

• Wind has the biggest impact on a wildfire.
• crown fires are spread by wind moving quickly
  across the tops of trees that are on fire
• one of the largest fires ever was in 1825 in
  Maine and Canada it burned over 3 million acres
• a really large wildfire can cause its own weather
  

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Top States Prone to Wildfires

1. California
2. Texas
3. Colorado
4. Washington
5. Idaho
6. Oregon
7. Arizona
8. Utah
9. New Mexico
10. Nevada

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WildfiresMain Features

• Wildfires can spread slowly from burning material
  along the forest floor or spread rapidly by wind
  causing it to jump along the tops of trees.
• Drought conditions, wind, high temperatures, and
  low humidity are conditions that help wildfires
  spread.

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Wildfire Impact

• A wildfire can destroy millions of acres of
  forest.
• Watersheds can have all the vegetation burned off
  leaving the area prone to erosion.
• Animals may become endangered due to habitat
  destruction.
• The economic losses can impact humans if fire
  sweeps through an inhabited area.
• New plant growth comes back quickly to a burned
  area.

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Bastrop State Park, TX
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Bastrop State Park, TX, 2011
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EARTHQUAKE
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EARTHQUAKE MAIN FEATURES

• An earthquake is the vibration of the Earths
  surface that occurs after a release of energy in
  the crust.
• This release of energy can be caused by a
  volcanic eruption or movement of segments of the
  crust (faults), or plate tectonic collisions.
• The crust may bend and as the stress builds and
  exceeds the strength of the rock, break, and snap
  into a new position.

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EARTHQUAKEMAIN FEATURES

• This process releases pressures in the crust and
  the Earths crust reaches equilibrium again.
• Seismic waves are created when the crust breaks.
• The waves travel outward from the source of the
  earthquake at various speeds, depending on what
  material they move through.

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IMPACT OF EARTHQUAKES

• Earthquakes can open large cracks in the ground
  causing standing bodies of water such as ponds or
  lakes to disappear.
• Land of either side of the fault can rise, lower,
  move away or toward each other.
• Earthquakes can cause damage to the environment
  by liquefaction of the ground, landslides,
  avalanches, fires, or tsunamis.
• The main impact to humans is property damage and
  loss of life.

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Worst in US History

• New Madrid, MissouriDecember 1811,
  morningRichter magnitude Estimated 8Damage
  Cracks opened in the ground some islands
  disappeared from middle of Mississippi River
  felt in Washington, D.C.

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New Madrid effects Landslide
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Cleburne, TX 2009
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TSUNAMI
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HOW TSUNAMI FORMS

• Tsunamis are ocean waves produced by earthquakes,
  volcanic eruptions, meteorite impact, or
  underwater landslides.

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TSUNAMIMAIN FEATURES

• Tsunamis are a series of waves that can travel
  between 450-600 mph in the open ocean.
• Ships in the open ocean would not feel the
  tsunamis because the wavelength would be hundreds
  of miles long and have amplitude of only a few
  feet.

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TSUNAMIMAIN FEATURES

• As the tsunami wave approaches the coast, its
  speed decreases and its amplitude increases.
• Basically, it gets slower and taller. From the
  starting point of the tsunamis, the waves travel
  outward in all directions.
• As the waves approach the coast, the time between
  each wave varies from 5-90 minutes.

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TSUNAMIMAIN FEATURES

• The first wave is usually not the largest or most
  destructive.
• Often the waters will pull back before the wave
  arrives.
• They are not v-shaped or rolling waves. Tsunamis
  often come ashore as a rapidly rising turbulent
  surge of debris filled water.

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WHERE TSUNAMIS OCCUR

• Tsunamis often come ashore as a rapidly rising
  turbulent surge of debris filled water.
• The waves can travel upstream in coastal
  estuaries and rivers.
• Tsunamis can occur during any season and at any
  time of day or night.
• Areas of risk are less than 25 ft. above sea
  level and within one mile of shore.

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IMPACT OF TSUNAMIS

• Impact includes drowning, flooding, contamination
  of drinking water, loss of habitat or human
  homes, fires from broken gas lines, etc.
• Both the environment and humans can suffer
  extreme damage from tsunamis.

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Tsunami wave hits Japan.
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Japan coastline
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HURRICANE
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HOW HURRICANES FORM

• Hurricanes start out as tropical storms (tropical
• cyclones).
• Moist, warm air above the ocean rises and cools
  forming clouds.
• Air from the oceans surfaces rushes into the
  space caused by the upward motion of the warm
  air.
• This air begins to spiral upward causing wind.
  When the winds reach a constant speed of 74 mph
  or more it is upgraded to a hurricane.

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HURRICANEMAIN FEATURES

• Hurricane winds blow in a spiral around a calm
  center called an eye.
• The eye can be up to 30 miles wide and the storm
  can be 400 miles in diameter.
• A single hurricane may last a week or more and
  travel the length of the East Coast.
• A hurricane can have torrential rains, high
  winds, and a storm surge as it approaches land.

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WHERE HURRICANES OCCUR

• On average, ten tropical storms develop over the
  Atlantic Ocean, the Caribbean Sea, or
• the Gulf of Mexico each year.
• About six of these develop into hurricanes. Many
  of these storms remain over the ocean.

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IMPACT OF HURRICANES

• Most deaths from hurricanes are due to flooding.
• Winds can drive ocean water up the mouth of
  rivers.
• Flooding can trigger mudslides or landslides.
  Tornadoes can be spawned by hurricanes.
• Economic costs and habitat loss is common.

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HURRICANE IKE

• September 18, 2008Gentle waves lap the shore
  near beach houses (top) on Texas'Gentle waves lap
  the shore near beach houses (top) on Texas'
  Bolivar Peninsula on September 9, 2008just a few
  days before Hurricane Ike rolled into Galveston
  Bay.
• An aerial photo of the same shoreline taken by
  the U.S. Geological Survey on September 15
  (bottom) illustrates the dramatic destruction the
  strong Category 2 storm wrought on the coastal
  community. Yellow arrows mark the same
  distinguishing features in both images.
• Unprotected by a seawall like the one built on
  nearby Galveston Island, homes along Bolivar's
  edge were among the hardest hit by Ike's massive
  10- to 15-foot (3- to 4.6-meter) storm surge.

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TORNADO
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HOW TORNADO FORMS

• Tornadoes in the winter and early spring are
  often associated with strong, frontal systems
  that form in the Central States and move east.
• Thunderstorms develop in warm, moist air ahead of
  eastward moving cold fronts while the cold, dry
  air is behind it to the west.

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HOW TORNADOS FORM

• These thunderstorms often produce large hail,
  strong winds and tornadoes.
• Along the mountains, tornado producing
  thunderstorms can form as the air flows up the
  slope to higher land areas.
• Tornadoes can form to the right and in front of
  the path a hurricane takes as it comes on land.

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TORNADOMAIN FEATURES

• A tornado is a violently rotating column of air
  extending from a thunderstorm to the ground.
• The most violent tornadoes have wind speeds of
  250 mph or more.
• Damage paths can be in excess of one mile wide
  and 50 miles long.

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TORNADOMAIN FEATURES

• Tornadoes may appear transparent until the dirt
  and debris it picks up gives it color.
• Two or more tornadoes may form at the same time.
• A waterspout is a weak tornado that forms over
  water.
• If the waterspout moves over the land it becomes
  a tornado.

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WATERSPOUT???
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Where Tornados Occur

• Tornadoes are most likely to occur between 3 and
  9 p.m., but have been known to occur at all hours
  of the day or night.

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IMPACT OF TORNADOS

• The high winds from the tornado and the hail from
  the thunderstorm cause the most damage.
• Tornadoes can destroy buildings and vehicles,
  kill humans and animals, uproot trees, and scour
  the soil off the ground down to the rock.

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Joplin, MO May 2011
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Joplin, MO May 2011
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FLOOD
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HOW FLOODS FORM

• A flood is an overflowing of water onto land that
  is normally dry.
• A flood can be caused by intense or long term
  precipitation from thunderstorms, hurricane storm
  surges, or melting snow and ice.

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FLOODMAIN FEATURES

• Floods can last from a few minutes to months.
• The amount of flooding is controlled by the
  amount of water that builds up as well as how
  porous the soil is and the amount of water
  already in the soil.

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WHERE FLOODS OCCUR

• Humans have altered the landscape in several
  ways.
• The greatest impact results from paving the
  ground for housing, roads, and parking lots.
• Neither asphalt nor concrete is porous.
• All the precipitation that falls becomes runoff
• Most of the worlds population lives near the
  coast or on floodplains.

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IMPACT OF FLOODS

• Floods can cause loss of life, disease, property
  loss or damage, contamination of drinking water,
  and destruction of crops and livestock.

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Ft Worth, TX 2007
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Damaged crops
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Flood damage.
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Turn Around, Dont Drown.
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Benefits of All of these Catastrophic Events

• Earths way of maintaining equilibrium
• Pressures or imbalances equalize through these
  processes.
• (YOUR flipbooks should contain these sentences in
  your Benefits Lists in addition to notes you
  took during class.)