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Tsunamis

VIEWS: 8 PAGES: 15

									  Tsunamis




Jonny and Danny
What are Tsunamis?
WHAT IS A TSUNAMI? –
• A wave train, (or series of
waves), generated in a body of
water, by a disturbance that
vertically displaces the water
column.
• Essentially, Tsunamis are
caused/triggered by other
natural hazards.
• Tsunamis savagely attack
coastlines, causing devastating
property damage and loss of
life.
Tsunamis can:
  – Travel 500km/h
  – Be 30 (up to 100) feet
    high (10m up to 30m)
  – Flood several hundred
    metres inland
  – A tsunami consists of a
    series of waves. Often
    the first wave may not
    be the largest.
  – Sometimes a tsunami
    causes the water near
    the shore to recede,
    exposing the ocean
    floor.
  – Large rocks weighing
    several tons along with
    boats and other debris
    can be moved inland
    hundreds of feet by
    tsunami wave activity.
  – Tsunamis can travel up
    rivers and streams that
    lead to the ocean.
WHAT ARE THE
 Explosions, landslides and Earthquakes
 provide energy that ?
CAUSES OF TSUNAMIS violently displaces
the water upwards

                      –
         Tsunamis “Land”
 Earthquake                            Eruption
         • Tsunamis are large water waves,
                     Slide
         typically generated by seismic
         activity, that have historically
This energy Travels as a wave, easily
         caused significant damage to
         coastal communities throughout the
propagated through the ocean
         world.

    How do landslides, volcanic eruptions and
    cosmic collisions generate Tsunamis ? –
    •Tsunamis can be generated by any disturbance that
    displaces a large water mass from its equilibrium
    position.

    • Earthquakes, explosions, and even the impact
    of cosmic bodies (i.e. meteorites) can generate
    tsunamis.
•Earthquake generated Tsunamis – Water
column disturbed by the uplift/subsidence
of the sea floor.
•A violent submarine Volcanic eruption can
create an impulsive force that uplifts the
water column and generates a Tsunami.
• Super marine landslides and cosmic body
impacts disturb the water from above.
Tsunamis generated from these mechanisms
dissipate quickly and rarely affect
coastlines distant from the source area.
The island of
  La Palma, in the
  Canaries is
  unstable.
Half a Trillion
  tonnes of rock
  could slip into
  the sea at any
  time.
The Tsunami
  generated could
  be 500m high,
  travel at 800km/h
  and could
  potentially
  destroy the
  American East
  coast.
   Where do Tsunamis
        Happen?
Tsunamis occur on
coastlines of
            Japan
wide oceans, with
active plate
boundaries within
close proximity
Japan, Australia,
        New Guinea
New Zealand and
the USA are prone
to Tsunamis in
the Pacific
Japan is famous
for Tsunamis,
which means
“harbour wave”
They occur when
the energy of the
wave hits
shallower water,
so are very
dangerous to land
on shallow
continental
shelves.
Impacts of Tsunamis
          • Social Impacts
            – People Killed
            – Homes and Business
              Destroyed
            – Livelihood lost
            – Homelessness
            – Lack of Basic
              Amenities
            – Disease
            – Forced Migration
• Economic Impacts
  – Businesses Damaged
  – Loss of Tourism
  – Loss of Earnings
  – Cost of
    Repair/Defence
  – Cost of Insurance
  – Harbours/Fishing
    Fleets Damaged
  – Agriculture Damage
      • Land Flooded
      • Salinisation
      • Livestock
        Drowned/Diseased/
        Escaped
• Environmental
  Impacts
  – Habitats Flooded
    • Salinisation
    • Fresh Water
      Sources Become
      Salty
    • Food Sources Lost
    • Shelter Lost
    • Forced Migration
  – Animals Killed
    • Drowned
    • Disease
  – Reefs Damaged
LEDC: Papua/New Guinea
• 17th July, 1998
• Caused by a 7.0
  Earthquake, on a
  Sub-ducting
  Boundary.
• 3 Successive
  Waves
                     Sissano Lagoon
• Villages of
  Sissano, Warupu,
  Arop and Malol
  destroyed
Impacts in New Guinea
           • AT LEAST 2100
             people killed.
           • 5,000+
             displaced
           • 15,000 people
             lived in
             Tsunami area
           • Trees uprooted,
             farmland
             flooded, debris
             up to 500m
             inland
MEDC: Japan
     • Japan experiences
       tsunamis because of
       its location in the
       Pacific, and close to
       tectonic boundaries.
     • They can flood large
       areas of the
       predominantly coastal
       communities.
     • They are engrained
       within the Japanese
       psyche, causing a
       great deal of fear
       around Japan.
     • July 1993– 7.8
       earthquake, 180+
       killed, $600million
       in damage.
     Impacts on Japan
• Huge economic
  loss
• Fishing industry
  damaged
• Cost of
  monitoring, and
  coastal defences.
• Relatively low
  death toll
• Impact on
  Japanese
  “fatalistic”
  psyche

								
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