Numerical modeling of waves for a tsunami early warning system

Chapter 1
Introduction
1.1 Tsunami
In the Coastal Engineering international scientific community, tsunamis are
long water waves triggered by a sudden disturbance of the sea/ocean floor or
the sea/ocean surface, which is usually caused by earthquakes, landslides or
volcanic eruptions. The word tsunamis comes from the Japanese, with the
meaning “harbor wave”, and is related to the excitation of seiches induced
into a harbor when the long tsunamis wave enters the closed basin. Both
energy and momentum can take tsunamis waves thousands of kilometers
across open ocean, carrying destruction on far shores hours after the impulse
generating event. In deep water conditions, tsunamis can travel at celerities
of 600-800 kilometers per hour, presenting wave heights of the order of some
centimeters, wavelengths of the order of hundreds of kilometers. As the wave
approaches shallow water near the coast, the wave celerity is reduced and the
wave height significantly increases, sometimes exceeding also the value of 20
meters, with wave periods up to 20/30 minutes. Tsunamis are able to produce
high wave runups which can flood the coastal areas and even destroy a city
in the coast, and they are so destructive and dangerous even because can
be rarely detected in open seas. Therefore it is very important the analysis
of this phenomenon, especially considering the safety aspects related to the
human activities along the coasts. Tsunamis waves have largely occurred
in the oceans and well known is the tragic event of Sumatra Island, in the
Indian Ocean, occurred the 26 th of December 2004 which caused the loss
of about 300,000 human life; however very dangerous events have been also
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