What we all witnessed recently in Japan was a shocking reminder of how incredibly powerful the forces of nature can be, none more so than earthquakes, ripping countries apart and causing untold devastation and loss of life, but perhaps more still is the terrifying sight of a huge wall of water, unstoppable and deadly, speeding towards land, metres high, at unbelievable speeds. These are the dreaded Tsunamis, formed throughmulti-stage process beginning with the enormous energy released when an earthquake happens under the ocean
First , the movements of tectonic plates against each other will cause a thrusting upwards of a section of the sea floor, sometimes by several meters. This huge land movement, sometimes kilometers in length, displaces vast quantities of sea water in the blink of an eye, causing this to begin flowing away from the epicenter in ever-widening circles, right across the ocean depths. The energy released by the quake was so vast that the water is propelled at great speed, very quickly, reaching up to a staggering 500mph.
Because the sea can be extremely deep, this speed of motion may not be immediately apparent on the surface, the oscillating nature of the travelling waves extending out as far as 60 to120 miles. Wave amplitudes can also be very small , the great spread of the wave making it, at sea, no more than five or six feet high, and longer times between wave crests making the detection of these waves out at sea very difficult.
Unfortunately, tsunami’s waves, once started, inevitably carry on building in speed and force, before finally coming in to hit a land mass blocking their path. The sea gets shallower, as the floor beneath it starts sloping upwards, towards the coastline, acting as a brake for the speeding tsunami waves, due to immense friction between them and the rising.land beneath.
Typically, the speed of the waves is cut by 90% , but the bad aspect of this is that the length of the waves is dramatically shortened, making them bunch up so much that wave heights increase a great deal, sometimes as much as 100ft above the level of the coastline facing them, this awesome event happening with unbelievable speed. This now highly compressed body of water surges forward, in an unstoppable wave of destruction that carries everything before it, trees, buildings, cars, boats and people sometimes for long distances inland.
It is often these initial, crushing waters that do most damage, not the giant waves that always follow them, as was clearly evident in all the awful footage of events that transpired as the recent Japanese tsunami swept inland. Research into the causes of these freak waves, and attempts to track formation of them has increased greatly over the past two hundred years, the global oceans these days monitored by tsunami detection and prevention centers, like the Pacific Tsunami Warning Center based in Honolulu, Hawaii.
Run by the National Oceanic and Atmospheric Administration, and set up back in 1949, series of tsunami monitors deliver oceanographic and seismic data to it daily, information transfer to other stations by satellite, responsible for detecting and predicting any approaching tsunamis around the Pacific ocean
Construction techniques and materials have, thankfully, become much better developed to aid in tsunami protection during the past century. The west coast of Japan is fitted with large-scale sea walls, artificial deep-sea barriers, and more, Japan being the best prepared country on earth for such catastrophes, but something on the scale of the recent disaster could never be planned for, if truth be told.
The Indian Ocean tsunami of 2004 claimed a total of 200,000 lives, and may be seen by some as far more catastrophic than that suffered by Japan, but the stark truth is that, no matter how well we think have prepared our defenses in advance, nature is simply too strong to be held at bay, when she exercises her fury on such a gigantic and destructive scale as she does whenever an earthquake ruptures the sea floor.
Tsunamis are, without a doubt, the most destructive natural force humanity is obliged to face, and unless we develop technology that will allow us to finally, accurately predict when and where big seismic events are going to occur, humanity will forever be at the mercy of a natural phenomenon that can never be contained, but will have to be endured many, many more times, somewhere in the world. Of that we can be absolutely sure.