EARTHQUAKES AND TSUNAMI IN JAPAN

Abstract

Japan is the nation with the most recorded tsunamis in the world. The event of March 2011 was seen all around the world practically in real time and in high-definition pictures; and that shows clearly the destructive power of this kind of natural catastrophe. The earthquake that unleashed that tsunami occurred on the ocean floor, close to Sendai Bay. It was the most powerful seismic event to have hit Japan, and of the most powerful ever recorded across the world. In this article we will discuss how earthquakes trigger tsunami waves, the so-called seismogenic tsunamis. We will see that there are
other possible causes for tsunamis, and not all earthquakes on the ocean floor can generate that kind of wave. The shape and speed of tsunami waves are different from those of common breakers. Finally, a comment is made on risk areas, drawn from the comparison of tsunamis throughout historical time and geological time. As phenomena of such magnitude are rare in historical time, it is necessary to search for evidences of tsunamis in geological records – when time is measured in millions or hundreds of millions of years – so as to have a more in-depth assessment of possibilities of occurrence of big tsunamis.