Tsunami is a Japanese word, wherein 'Tsu' means harbor, and 'nami' means wave. It can be described as the wall of water that can challenge a jet plane moving with speed. This word is used globally to refer to a series of waves of extremely long wavelength and long period, generated by an impulsive disturbance which causes displacement of the water.
These waves have enough strength to cause mass destruction of life and property. As these waves approach the land, their appearance and behavior become dependent on several factors. The most important factors are the topography of the seafloor and shape of the shoreline.
What Causes a Tsunami?
➤ Seismic disturbances, volcanic activities, and submarine faulting are the main reasons for occurrence of such a series of waves. A seismic disturbance can move the seawater, causing a rise or fall in the level of the ocean. Such disturbances occur due to the displacement of tectonic plates.
➤ Tsunamis are primarily related to earthquakes in oceanic and coastal regions. After an earthquake occurs, the energy travels outward in all directions from the epicenter. The amount of time between consecutive waves, known as the wave period, is only a few minutes to an hour.
As this wave crosses the ocean, its length from one crest to the other may be around hundred miles, and its vertical height may be from a few feet to more than 30 m.
In the deepest part of the oceans, the waves will touch speeds of 600 -750 miles per hour, traveling across the ocean in less than a day. These can reach a maximum vertical height onshore, above sea level, called a run-up height of 30 meters.
➤ The Pacific Tsunami Warning System (PTWS) is one of the warning systems established in 1948 for the United States and its territory. By 1965, it became an international system with 26 nations as its members.
Seismic stations operated by the PTWS are used for detection and location of such waves, and also perform the task of providing information about earthquakes.
➤ In case of any tectonic activity, the satellite initially monitors and sends warning to the PTWS. When this information received from tidal station reveals that a potentially destructive wave exists, an alert signal is passed on to all stations.
This message is then passed on to the member nations, and subsequently, the residents are warned about the upcoming disaster over television and radio.
➤ Early signs of series of such waves are aggressive vibrations of the Earth, but most of the earthquakes occur far away from the sea and thus, give little or no indication that a tsunami is on its way.
➤ If you stay nearby a sea area, make sure that you immediately turn off the water, gas, and electricity connections and swiftly move to a higher ground level. Bear it well in your mind, once a warning is issued, it could be a case of minutes or even seconds before the devil wave hits.
In most cases, the first wave proves to be less dangerous. These waves get swifter and worse as time passes. After the wave has hit, all food and water should be tested from a hygienic point of view before consumption. Each building (hit by tsunami) must be checked for gas leaks and electrical shorts before anyone entering its premises.
Recently, the tsunami wave occurred in the Indian Ocean, which hit the islands of Indonesia, Sri Lanka, Thailand, and Andaman and Nicobar, causing thousands of people to lose their lives. The help provided by citizens of all the countries was amazing, which just goes to show the unity of mankind in order to tackle natural disasters.