1. Tsunami Formation
As a tsunami leaves the deep ocean and travels toward the shallow coast, it transforms.
A tsunami moves at a speed related to the water depth, therefore the tsunami slows as the water depth decreases.
As a result, the tsunami's speed decreases as it travels into shallower water, and its height increases.
Because of this ‘shoaling effect’, a tsunami, unobvious at sea, may heighten to several meters or more near the coast.
When it reaches the coast, it may appear as a rapidly rising or falling tide or a series of breaking waves.

2. As they approach shallower water they slow down but the height of tsunami waves increase- this is called a ‘shoaling effect’

3. Tsunami Formation
As a tsunami reaches the shore, it begins to lose energy whereby part of its wave energy is reflected offshore, while the shoreward-propagating wave energy is dissipated through friction and turbulence.
In spite of this, tsunamis still reach the coast with tremendous amounts of energy

4. H/W :Example Question June 2013
02) Describe the characteristics and explain the causes of tsunamis. ( 8 marks)
Level 1:
Simple statements of characteristics/causes, lacking detail or sophistication of either features or processes.
Level 2:
Both elements must be present, detailed statements of characteristics and/or explanation, possibly with some use of supportive material. The answer progresses through the level as more is added at this level. Full mark answers show breadth of knowledge.

5. Tsunami Time Travel Maps These give a better understanding of how an event may occur and the potential RISKS for people living within a tsunami’s reach
See P.12 Hodder fig 1.16
A tsunami travel time map centred on an event in Hawaii.

6. Japan, March :Tsunami time- travel map to show the speed at which the wave spreads across the Pacific Ocean

7. Time travel map to show the arrival times of the Indian Ocean Tsunami’s first wave, Boxing day 2004

10. Time travel map showing the expected travel times of a tsunami centred on the location of an 8.6 magnitude earthquake off the coast of Indonesia Nov

11. TASK Ref Oxford (Geography for Edexcel A level Year 1 book)
Look at fig 6 p22
Answer question 2 ONLY on p.23
(you will need a pair of compasses)
EXTENSION Q
How useful do you think tsunami time travel maps
are with regard to minimising the risk for people
living within a tsunami’s reach?

12. WHITEBOARD THINKING … What do you think can be done to PREPARE, WARN
OR REDUCE THE IMPACTS OF A TSUNAMI??

13. Tsunami warning sign

14. Warning Signs- Tsunami
Quite often, the first warning given to local coastal populations is the wave trough in front of the tsunami which results in a reduction in sea level known as the ‘drawdown/drawback’( ie the sea seems to have been ‘sucked backwards away from the shore)
If you are ever on holiday and notice the sea behaving in this way- RUN TO HIGH GROUND!!

15. Warning sign on sea wall at kamakura, Japan

16. Sea wall defence at Tsu, Japan
Sea wall defence at Tsu, Japan. These were overtopped in the recent tsunami.

17. What has happened since 2004? (Management strategies..)
39 buoys are now deployed worldwide with nearly two dozen in the north Pacific.
It is costly and difficult to establish and maintain an observational network in deep water.
NOAA
DART® real-time tsunami monitoring systems

18. What has happened since 2004?
Indian Ocean Tsunami Warning and Mitigation System (IOTWS)
Although the expected frequency of this magnitude event in the Indian Ocean is 1 in 600 years, the scale of disaster meant immediate action.
IOTWS is very advanced– it has taken advantage of leapfrogging technology.
It uses earthquake information, tide gauges and tsunami detection buoys. Driven by USA but taken up by Australia, Chile, Indonesia and Thailand.
blog.petaflop.de

19. The DART Pacific Ocean tsunami warning system
The DART Pacific Ocean tsunami warning system. (Deep-ocean Assessment and Reporting of Tsunamis)

20. Timeline post 2004
We cannot forecast a tsunami event, but once generated, we can model its arrival and impact
NOAA

21. It’s not just technology that is needed if future tsunamis are to be less devastating…
Communications systems and integration
26 national tsunami centres in Indian Ocean
25 new seismographic centres sending data
3 deep ocean sensors
Warnings
Warned area: prepare for imminent flooding within 2 hours
Watch area:
For earthquakes over 7.0+ stay alert for I hour For earthquakes over 7.5+ stay alert for 3 hours
Hazard mapping and modelling
Local preparedness
Development of resilient communities.
Geohaz.org

22. An accurate final death toll may never be known but is estimated to be around 20,000. Prayer signpost

23. Watch excellent Ian Stewart programme on the Japanese earthquake and tsunami
(shared area..)