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Tsunamis

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.

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Tsunamis

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  1. Tsunamis Jonny and Danny

  2. 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.

  3. 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.

  4. Explosions, landslides and Earthquakes provide energy that violently displaces the water upwards WHAT ARE THE CAUSES OF TSUNAMIS ? “Land” Slide Earthquake Eruption Tsunamis – • Tsunamis are large water waves, typically generated by seismic activity, that have historically caused significant damage to coastal communities throughout the world. This energy Travels as a wave, easily propagated through the ocean • 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.

  5. 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.

  6. 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.

  7. Japan New Guinea Where do Tsunamis Happen? Tsunamis occur on coastlines of wide oceans, with active plate boundaries within close proximity Japan, Australia, New Zealand and the USA are prone to Tsunamis in the Pacific

  8. 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.

  9. Impacts of Tsunamis • Social Impacts • People Killed • Homes and Business Destroyed • Livelihood lost • Homelessness • Lack of Basic Amenities • Disease • Forced Migration

  10. 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

  11. Environmental Impacts • Habitats Flooded • Salinisation • Fresh Water Sources Become Salty • Food Sources Lost • Shelter Lost • Forced Migration • Animals Killed • Drowned • Disease • Reefs Damaged

  12. LEDC: Papua/New Guinea • 17th July, 1998 • Caused by a 7.0 Earthquake, on a Sub-ducting Boundary. • 3 Successive Waves • Villages of Sissano, Warupu, Arop and Malol destroyed Sissano Lagoon

  13. 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

  14. 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.

  15. 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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