1. The Effects of 8 Catastrophic Events that Impact Earth
7th Grade Science
PGMS
Great info. 1

2. 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.

3. VOLCANO

4. 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.

5. VOLCANO—MAIN FEATURES
A volcano is a vent in the Earth which allows molten rock (magma) to escape to the surface.

6. 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.

7. 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. 7

8. 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. 8

9. 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. 9

10. VOLCANOES

11. Mount Tambora--
Indonesia. Spread an ash cloud that covered the world. . 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. 11

12. Crater Lake, Oregon
Did You Know? At 1,943 feet deep, Crater Lake is the deepest lake in the United States and one of the ten deepest lakes in the world! 1,943 feet deep, Crater Lake is the deepest lake in the US and one of the 10 deepest in the world. 12

13. DROUGHT

14. 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

15. 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

16. Types of Drought
Meteorological - lack of precipitation
Agricultural - low soil moisture
Hydrological - lack of water in
watersheds,river systems, and reservoirs

17. 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

18. Texas Drought Monitor

20. Lake Travis 2007 20

21. Lake Travis, Aug. 2011 Pic taken Aug 2011 21

22. Wildfires

23. What is a wildfire? *
A wildfire is an uncontrolled fire.

24. 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 )

25. * 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

26. Top States Prone to Wildfires*
California
Texas
Colorado
Washington
Idaho
Oregon
Arizona
Utah
New Mexico
Nevada

27. Wildfires—Main 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.

28. 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.

29. Bastrop State Park, TX
About an hour drive or 40 miles southeast of Austin, Bastrop State Park encompasses an area of 5,926 acres and built up by loblolly pine and hardwoods. Located in central texas. 29

30. Bastrop State Park, TX, 2011
Flames engulf a road near Bastrop State Park as a wildfire burns out of control near Bastrop, Texas September 5, (Mike Stone/Reuters) # 30

31. EARTHQUAKE

32. EARTHQUAKE –MAIN FEATURES
An earthquake is the vibration of the Earth’s 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.

33. EARTHQUAKE—MAIN FEATURES
This process releases pressures in the crust and the Earth’s 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.
Seismic wave—general term encompassing all waves generated by an earthquake. 33

34. 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.

35. Worst in US History
New Madrid, Missouri December 1811, morning Richter magnitude: Estimated 8 Damage: Cracks opened in the ground; some islands disappeared from middle of Mississippi River; felt in Washington, D.C.
The New Madrid earthquakes (pronounced /nuː ˈmædrɨd/ (pronounced /nuː ˈmædrɨd/) were an intense intraplate earthquake series beginning with an initial pair of very large earthquakes on December 16, These earthquakes remain the most powerful earthquakes ever to hit the eastern United States in recorded history 35

36. New Madrid effects: Landslide 36

37. Cleburne, TX 2009
Central Plains Ecoregion 37

38. TSUNAMI

39. HOW TSUNAMI FORMS
Tsunamis are ocean waves produced by earthquakes, volcanic eruptions, meteorite impact, or underwater landslides.

40. TSUNAMI—MAIN FEATURES
Tsunamis are a series of waves that can travel between 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.

41. TSUNAMI—MAIN 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 minutes.
AMPLITUDE—height of the waves 41

42. TSUNAMI—MAIN 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.

43. 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.

44. 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.

45. Tsunami wave hits Japan. 45

46. Japan coastline 46

47. HURRICANE

48. 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.

49. HURRICANE—MAIN 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.

50. 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.

51. 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.

52. HURRICANE IKE
September 18, 2008—Gentle 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, 2008—just 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. 52

53. TORNADO

54. 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.

55. 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.

56. TORNADO—MAIN 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.

57. TORNADO—MAIN 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.
WATERSPOUT-- 57

58. WATERSPOUT???
WATERSPOUT--Waterspouts are similar to tornadoes over water. Waterspouts are generally broken into two categories: fair weather waterspouts and tornadic waterspouts. Tornadic waterspouts are simply tornadoes that form over water, or move from land to water. They have the same characteristics as a land tornado. They are associated with severe thunderstorms, and are often accompanied by high winds and seas, large hail, and frequent dangerous lightning.
Nat. Oceanic and Atmospheric Administration 58

59. 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.

60. 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.

61. Joplin, MO May 2011 61

62. Joplin, MO May 2011
Multiple-vortex tornado; 162 deaths. EF5 on the Fajita Scale. Ranks as one of the US most deadly tornadoes. 62

63. FLOOD

64. 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.

65. FLOOD—MAIN 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.

66. 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 world’s population lives near the coast or on floodplains.

67. IMPACT OF FLOODS
Floods can cause loss of life, disease, property loss or damage, contamination of drinking water, and destruction of crops and livestock.

68. Ft Worth, TX 2007 68

69. Damaged crops

70. Flood damage. 70

71. Turn Around, Don’t Drown. 71

72. Benefits of All of these Catastrophic Events:
Earth’s 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.)