Tsunamis are common throughout Japanese history; approximately 195 events in Japan have been recorded. A tsunami has a much smaller amplitude (wave height) offshore, and a very long wavelength (often hundreds of kilometers long), which is why they generally pass unnoticed at sea, forming only a passing “hump” in the ocean. Tsunamis have been historically referred to tidal waves because as they approach land, they take on the characteristics of a violent onrushing tide rather than the sort of cresting waves that are formed by wind action upon the ocean (with which people are more familiar).
Since they are not actually related to tides the term is considered misleading and its usage is discouraged be oceanographers. A tsunami can be generated when the plate boundaries abruptly deform and vertically displace the overlying water. Such large vertical movements of the Earth’s crust can occur at plate boundaries. Sub induction earthquakes are particularly effective in generating tsunami.
Tsunami take place when a huge earthquake occurs causing the plates below the water to push up causing the water to create a huge wave. In the 1950s it was discovered that larger tsunami than previously believed possible could be caused by landslides, explosive volcanic action, and impact events when they contact water. These phenomena rapidly displace large volumes of water, as energy from falling debris or expansion is transferred to the water into which the debris falls.
Tsunami caused by these mechanisms, unlike the ocean-wide tsunami caused by some earthquakes, generally dissipate quickly and rarely affect coastlines distant from the source due to the small area of sea affected. However, an extremely large landslide could generate a “mega tsunami” that might have ocean-wide impacts.
The geological record tells us that there have been massive tsunami in Earth’s past historically speaking, tsunami are not rare, with at least 25 tsunami occurring in the last century. Of these, many were recorded in the Asia- Pacific region – particularly Japan. The Boxing Day Tsunami on Boxing Day 2004 caused approx. 300,000 deaths and many more injuries. The destruction of the Egyptian city of Alexandria in A.D.365 is now presumed to have been caused by a tsunami. The effects of a tsunami can be mitigated by natural factors such as tree cover on the shoreline.
Some location in the path of the 2004 Indian Ocean tsunami escaped almost unscathed as a result of the tsunami’s energy being sapped by a belt of trees such as coconut palms and mangroves. In one striking example, the village of Naluvedapathy in India’s Tamil Nadu region suffered minimal damage and few deaths as the wave broke up on a forest of 80,244 trees planted along the shoreline in 2002 in a bid to enter the Guinness Book of Records. Environmentalists have suggested tree planting along stretches of seacoast which are prone to tsunami risks.
While it would take some years for the trees to grow to a useful size, such plantations could offer a much cheaper and longer-lasting means of tsunami mitigation than the costly and environmentally destructive method of erecting artificial barriers. While it is not possible to prevent a tsunami, in some particularly tsunami-prone countries some measures have been taken to reduce the damage caused on shore. Japan has implemented an extensive programme of building tsunami walls of up to 4.5 high in front of populated coastal areas.
Other localities have built floodgates and channels to redirect the water from incoming tsunami. However, their effectiveness has been questioned, as tsunami is often higher than the barriers. Because in the end nature can act in certain ways which one can only and only imagine. The time we take the necessary steps in order to calm this nature’s fury- and the answer to that is curbing global warming on a large scale worldwide.