<p>Surges are usually produced by the action of the wind on the water surface and their waves usually have a rhythm of 20 seconds and propagate 150 meters inland at the most, as we see in storms or hurricanes. The propagation is limited by distance, so it loses intensity when moving away from the place where the wind is generating it.<br /><br />A TSUNAMI, on the other hand, presents an opposite behavior, since the sudden movement of the water creates a &ldquo;whiplash&rdquo; effect from the depths towards the surface which is able to achieve waves of unthinkable magnitude. Mathematical analysis indicates that the velocity equals the square of the product between the force of gravity (9.8 m/s2) and depth. To have an idea let&rsquo;s take the regular depth of the Pacific Ocean, which is 4,000 m; it would give us a wave that could move at 200 m/s, i.e. 700 km/h. And since wave lose their strength inversely in relation to their size; having 4,000 m may travel a distance thousands of miles without losing much strength.<br /><br />They only lose strength when reaching the coast, when the ocean&rsquo;s depth decreases. The height of the waves, however, can increase over 30 meters (the usual height is 6 or 7 m).<br /><br />The faults present at the coasts of the Pacific Ocean where the tectonic plates are suddenly introduced under the continental plate causes a phenomenon called &ldquo;subduction&rdquo;, which generates TSUNAMIS frequently. Landslides and submarine volcano eruptions may cause similar phenomenon.<br /><br />The energy of TSUNAMIS keeps more or less constant during their displacement, so when reaching to more shallow areas, since there is less water to displace, the velocity is formidably increased. A TSUNAMI felt like a large wave at open seas can destroy miles inland when reaching the coast. The turbulence produced at the bottom of the sea drags rocks and sand that causes erosive damage at the beach, alternating the geography for many years.&nbsp;&nbsp;&nbsp; <br /><br />Japan is the country hit by more TSUNAMIS as a result of its geographic location.<br />&nbsp;</p>