Tsunamis occur most frequently in the Pacific, particularly along the "Pacific Ring of Fire ". This zone is found at the northern edge of the Pacific Plate and refers to the geologically most active fields of the earth. Several times a year, strong earthquakes of at least 7 on the Richter scale result in tsunamis. Japan, for example, is hit by a tsunami at least once a year. From observations of scientists and historical sources, we know today that Tsunamis can occur in all larger seas of the world. Thus, fatal tsunamis occur in geologically less active oceans such as the Atlantic, the Indian Ocean or the Mediterranean as well. Great danger exists in densely populated areas or in vacation areas in which a tsunami can endanger millions of human lives. Though Tsunamis occur more often in, for example the Mediterranean than in the Pacific Ocean, but that is exactly why we should not underestimate or minimize the danger. Looking back to the year 1755 we can see that the tsunami triggered by the earthquake off Lisbon is accountable for the majority of the 70 000 deaths.