WHEN TSUNAMI HAPPENS?
➡A tsunami happens when underwater earthquakes result in sudden vertical deformation of the seafloor; thus, the section of Earth's crust under or near the ocean rises or falls. It creates a sudden rise or fall of the crust under or near the ocean that produces vertical displacement of the seafloor, which in turn displaces water above. When a plate shoots upwards, it pushes the water up with it and forms a wave when the energy from Earth's crust is transferred to the water. Vertical displacements of the seafloor are triggered by thrust faulting, reverse faulting, and normal faulting where compression pushes the rock on one side of the fault up and over rock on the other side. These faulting occur along subduction zones where two tectonic plates bump into and move toward each other, with one sliding underneath the other.Large and shallow-focus earthquakes with an epicenter or fault near or on the ocean floor cause significant vertical deformation of the seafloor generate tsunami.Therefore, magnitude 7 or 8 earthquakes cannot produce tsunami unless they involve sudden vertical movement over a long area of a fault. If the movement of the crust causing large undersea earthquake is horizontal, then the overlying water is not displaced, and therefore there is less risk of tsunami because water is virtually immune to the horizontal shearing motion of the ocean floor; hence, little water is displaced Most damaging tsunamis occur in the Pacific Ocean where the Ring of Fire is known to be in its boundary, and in the Indian Ocean where there are two major subduction zones. Earthquakes are most frequent in these regions.
