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Earthquakes: Tsunamis can be generated when the sea floor abruptly deforms and vertically displaces the overlying water. Tectonic earthquakes are a particular kind of earthquake associated with the earth's crustal deformation. When they occur beneath the sea, the water above the deformed area is displaced from its equilibrium position. Waves are formed as the displaced water mass attempts to regain its equilibrium. When large areas of the sea floor elevate or subside, a tsunami can be created. Large vertical movements of the earth's crust can occur at plate boundaries. Plates move along these boundaries called faults. For example, around the margins of the Pacific Ocean, denser oceanic plates slip under continental plates in a process known as subduction. Subduction earthquakes are particularly effective in generating tsunamis. Landslides, Volcanic eruptions, cosmic collisions A tsunami can be generated by any disturbance that displaces a large water mass from its equilibrium position. Submarine landslides, often accompanying large earthquakes, as well as collapses of volcanic edifices, can also disturb the overlying water column as sediment and rock move downwards and are redistributed across the sea floor. Similarly, a violent submarine volcanic eruption can create an impulsive force that uplifts the water column and this results in a tsunami. Conversely, marine landslides and cosmic-body impacts disturb the water from above, as momentum from falling debris is transferred to the water. Generally, tsunamis generated from these mechanisms, unlike the Pacific-wide tsunamis caused by some earthquakes, dissipate quickly and rarely affect coastlines distant from the source area. Back (What does "tsunami" mean?) | Next (Characteristics of a Tsunami) |