Tsunami

The word 'tsunami' comes from the Japanese words for harbor (tsu) and wave (nami). It refers to a series of giant undersea waves that travel at high velocity for very long distances, and that crest when they hit a shoreline in the form of a devastating surge, sometimes as much as 30 meters high. Tsunamis are often called 'tidal waves' but that's a misnomer: the phenomenon has nothing to do with the tides. It has its origins, like everything else that involves the earth's surface, in plate tectonics.It is hard to imagine that the theory of plate tectonics, which is at the heart of all modern geological science, is only a hundred years old and was not widely accepted until the 1970s. Schoolchildren had noticed for hundreds of years that the facing shapes of South America and Africa could be fitted neatly together like pieces of a jigsaw puzzle to make a single entity (Francis Bacon had noticed it in 1620 but drew no conclusion), but it wasn't until 1908 that the amateur American geologist Frank Bursley Taylor proposed that the continents had once slid around and that this motion might have thrust up the world's mountain chains. His theory was taken up by the German planetary astronomer-turned-meteorologist Alfred Wegener, who in 1912 proposed that all the world's continents had once been part of a single giant landmass he called Pangaea, which had split apart in a process of lateral motion that was still continuing. Traditional geologists attacked both Wegener and his ideas viciously, and it wasn't until the decade after his death (he froze to death on a scientific expedition in Greenland in 1930) that the great English geologist Arthur Holmes provided an explanation for how Wegener's motion could occur. In a textbook published in 1944 he speculated that heat caused by the decay of radioactive elements in the earth's crust could produce powerful convection currents that could slide the continents around on the earth's surface. He has probably as good a claim as anyone