Describe how a tsunami is generated. Explain how tsunami warning systems are
used to help forecast tsunami events. Choose a recent tsunami event and describe
the history of its occurrence, as well as its impacts on human beings.
Tsunamis can be generated when the sea floor abruptly deforms and
vertically displaces the overlying water. Tectonic earthquakes are a
particular kind of earthquake that are associated with the earth's
crustal deformation; when these earthquakes occur beneath the sea, the
water above the deformed area is displaced from its equilibrium
position. Waves are formed as the displaced water mass, which acts
under the influence of gravity, attempts to regain its equilibrium.
When large areas of the sea floor elevate or subside, a tsunami can be
Large vertical movements of the earth's crust can occur at plate
boundaries. Plates interact along these boundaries called faults.
Around the margins of the Pacific Ocean, for example, denser oceanic
plates slip under continental plates in a process known as subduction.
Subduction earthquakes are particularly effective in generating