What are tsunamis or "tides of death"

King tides earthquake: this is the meaning of the Japanese word tsunami.

 "They are huge waves over 30 meters high, caused by disturbances in the depths of the sea, like earthquakes (tsunamis), volcanic eruptions and even landslides on the ocean floor,"

 says physicist Joseph Dias Edmo Campos, the Oceanographic Institute USP. The tremors caused by geological phenomena like these cause a lot of ripples spreading over large distances on the ocean surface. 

These waves are initially quite long and low, no more than 0.3 to 0.6 meter. 

The crew of a boat passing over them is not able to perceive them - and their energy can diminish and disappear, to roam thousands of miles.

 The problem occurs when they approach shore, where the depth decreases and appears friction with the ocean floor. 

The result is that become compressed by an ever smaller space, forcing them to rise. By then, the tsunamis form a column, sucking the sea coast to the point of leaving part of the ocean floor discovered. This is the last warning. Minutes later, they appear. To get an idea, one of the worst tides of the genre, which occurred in 1703, on the Japanese island of Awa, killed over 100 000 people.