Tsunamis are catastrophic ocean waves usually caused by underwater earthquakes or volcanic eruptions. As the waves enter shallow coastal waters, their speed decreases and wavelengths shorten, causing wave amplitudes to rapidly increase in height up to 30 meters. The 2004 Indian Ocean tsunami was particularly devastating, killing over 230,000 people across 14 countries after a massive earthquake near Indonesia generated waves. While most tsunamis are small, some earthquakes near tectonic plate boundaries can trigger highly destructive waves over 100 meters tall.

1. . Tsunami Phenomenon

2. The word Tsunami comes from Japan where it has been a frequent phenomen and originally meant a wave in harbor. Before there was a clear understanding of the tsunami phenomenon, Japanese fishermen would often return home from sea trip and observe their harbor aread devastated by water. They have experienced nothing while sailing on the open sea so they described tsunami phenomenon as a wave in harbor.

3. Tsunami is a catastrophic ocean wave, mostly caused by a submarine earthquake less than 50 kilometers under the seafloor with a magnitude greater than 6.5 on Richter scale. Near the source of submarine earthquakes, the seafloor is “permanently” uplifted and down-dropped, pushing the water up and down. The potential energy from pushing water is transformed to kinetic energy seen as the tsunami wave

4. Even if a wave is 15 meters high (not likely in tsunamis) it makes a little difference in a hundred meters deep water but, as it comes into shallow water, the wave rises much higher and strikes the shore with very devastating force. In deep water wavelengths are enormous (100km to 200km) and wave heights are pretty small, less than 1 meter but as the waves approach the continental coasts, shallow water reduces the speed of the waves shortening the wavelengths and amplifying wave amplitudes up to 30 meters in just 10 to 15 minutes what is very fast transition. Tsunamis can be also caused by landslides or volcanic eruptions

5. Most of tsunamis don’t result in giant destructive waves but some, such as the 2004 Indian Ocean event, are very devastating, both for structures and inhabitants. Offshore earthquake near Indonesian Island of Sumatra caused deadly tsunami that killed more than 230,000 people in 14 different countries, mostly in Indonesia, Sri Lanka, India and Thailand. Earthquake that caused tsunamis was the third largest earthquakes recorded in human history, with magnitude of between 9.1 and 9.3 on Richter scale. Most of the earthquakes causing dangerous waves and tsunamis are happening on the edges of tectonic plates in areas like Alaska, California, South America and Indonesia