Natural%20Hazards-How%20they%20occur - PowerPoint PPT Presentation

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Natural%20Hazards-How%20they%20occur

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Natural Hazards-How they occur Earthquake 1. Moving of tectonic plates Earthquake Earthquake Earthquake There are 4 types 1. Follows the line of mid-ocean ridges ... – PowerPoint PPT presentation

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Title: Natural%20Hazards-How%20they%20occur


1
Natural Hazards-How they occur
2
Earthquake
  • 1. Moving of tectonic plates

3
Earthquake
  • 2. Stress builds up between plates because the
    plates break apart or get stuck as they move past
    each other.
  • 3. The stress causes the plates to bend.
  • 4. Eventually the stress is too much and the
    plates slip apart, suddenly releasing a huge
    amount of energy.

4
Earthquake
5
Earthquake
  • There are 4 types
  • 1. Follows the line of mid-ocean ridges
  • Small quakes occurring at shallow depths
  • Example Iceland

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7
Earthquake
  • 2. Shallow-focus event unaccompanied by volcanic
    activity
  • In these faults, 2 plates are creating great
    friction between them and building up large
    strains
  • Quake activity doesnt always occur along the
    entire fault line.
  • Example San Andreas Fault

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9
Earthquake
  • 3. Collision of oceanic and continental plates
  • Oceanic plate is subducted under the continental
    plate -gt deep ocean trenches, associated with
    curved volcanic island arcs
  • This type of earthquake can be shallow,
    intermediate or deep depending on the location on
    the down-going lithospheric slab.
  • Example Along the Peru-Chile trench

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11
Earthquake
  • 4. Along boundaries of continental plates
  • Shallow, intermediate and deep-focus earthquakes
    occur
  • Associate with high mountain ranges
  • Example Himalayas

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13
Tsunami
  • The earthquake needs to be at least a 7.0
    magnitude to create a tsunami.

14
Tsunami
15
Tsunami
16
Mudslide/Landslide
  • 3 things for landslide to happen
  • A slope
  • Unstable earth on slope
  • Water (I.e. storms, melting snow)

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18
Mudslide/Landslide
  • From rainfall
  • 1. Occurrence of storm or melting of snow
  • 2. The water liquefies the soil on steep slope
  • 3. The soil becomes moistened and starts flowing
    downhill
  • 4. The destruction of properties

19
Mudslide/Landslide
  • From Earthquake
  • 1. Occurrence of earthquake
  • 2. The soil moves during the quake on steep
    slopes
  • 3. Soil slips and causes mudslide/landslide

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21
Volcano Eruption
  • 1. The pressure on a magma chamber deep below the
    Earth's surface begins to build up
  • 2. This building pressure causes the magma from
    the chamber to be forced upward through a series
    of tubes
  • 3. Molten rock (magma) and ashes will start to
    billow out (explosive eruptions) or lava will
    flow heavily down the side of the volcano with
    little to no ash (non-explosive eruptions).

22
Mt. St. Helens - Washington State
23
Hurricanes
  • Temperature of water must be at least 80 degrees
    Fahrenheit

24
Hurricanes
  • 1. Warm, moist air from the ocean rises rapidly.
  • 2. Water vapor condenses and builds storm clouds
    and rain droplets.
  • 3. Condensation releases heat
  • 4. The heat warms the cool air, causing it to
    rise.
  • 5. Then, the rising air is replaced by more warm,
    humid air from the ocean.
  • 6. This cycle continues
  • 7. Wind speed is at 74mph and above

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