6. Next Slide

8.  Most Tsunamis are caused by earthquakes generated in a subduction zones, an area where an oceanic plate is being forced down into the mantle by plate tectonic forces.  The friction between the subducting plate and the overriding plate is enormous.  This friction prevents a slow and steady rate of subduction and instead the two plates become "stuck".

9.  As the stuck plate continues to descend into the mantle the motion causes a slow distortion of the overriding plage.  The result is an accumulation of energy very similar to the energy stored in a compressed spring.  Energy can accumulate in the overriding plate over a long period of time - decades or even centuries.

10.  Energy accumulates in the overriding plate until it exceeds the frictional forces between the two stuck plates.  When this happens, the overriding plate snaps back into an unrestrained position.  This sudden motion is the cause of the tsunami - because it gives an enormous shove to the overlying water. At the same time, inland areas of the overriding plate are suddenly lowered.

11.  The moving wave begins travelling out from where the earthquake has occurred.  Some of the water travels out and across the ocean basin, and, at the same time, water rushes landward to flood the recently lowered shoreline.

13. Next Slide Location: Tokyo, Japan. Date: 11 th March 2011 (Friday) Power : 8.9 Magnitude. Duration: 41 secs.

14. Next Slide Location: Tokyo Airport, Japan. Date: 11 th March 2011 (Friday) Power : 8.9 Magnitude. Duration: 41 secs.

15. Next Slide Explosion in Nuclear Reactors, Japan. Date: 11 th March 2011 Power : 8.9 Magnitude. Duration: 41 secs.

17. The technical and social components of a system for warning, communication and actions to take in the event of tsunami are:  Seismographs  Data Processing Centers  Communications Systems  Education of Populations

18. In regions at risk, a sufficient number of seismographs should be in place. An extensive network of seismographs should be organized that would detect and register any vibes from undersea earthquakes. It is fundamental that these seismographs should undergo regular maintenance and be upgraded whenever technical evolutions impose it.

19. It is important to establish regional data processing centers. The immediate expert reading and interpretation of the collected data, will allow predictions for tsunami type phenomena, the time that they may occur, their intensity and the regions that will be affected.

20. Adequate communications systems should be installed that will be able to quickly transfer internationally, alarms and warnings to populations and communities in areas that are in immediate danger. Alarm sirens that will warn people should be tried and installed. All these systems should be regulated by specific protocols and readily functional.

21. People who live in areas at risk, should be educated in matters relevant to earthquakes and tsunamis. Additionally they should be taught in advance how to react and what to do in case that such a disastrous phenomenon occurs. Planning should be done to determine safe grounds for the inhabitants of endangered localities and for providing the means for them to escape.