Tsunami
By Anuj Thakkar
Tsunami
Tsunamis (or Tidal Waves) are series of waves in a body of water caused by the displacement of a large volume of water, generally in an ocean or a large lake. Potential tsunami generators are Underwater Earthquakes, Volcanic Eruptions and other Underwater Explosions.
The History of the Tsunami
The term tsunami, meaning "harbor wave", comes from Japanese roots (津波). While Japan may have created the term, they are by no means the only area to get them. In fact, the Roman Historian Ammianus Marcellinus described such a tidal wave, after the 365 AD tsunami that devastated Alexandria.
Causes
What generally causes a Tsunami is a natural/unnatural occurrence that displaces a substantial amount of water. Most causes are underwater:
- Earthquakes (Seismic Activity)
- Volcanic Activity
- Landslides (Above Surface Level)
- Meteorological Conditions
- Any Other Tectonic Disturbance
Seismic Activity
Tsunamis can be generated when the sea floor deforms (abruptly) and displaces the overlying water. When the overriding plate bulges under the strain causing tectonic uplift. When the Plate slips, it causes subsidence (motion of a surface) and releases energy into water. the energy released produces/displaces water, forming a tsunami wave.
Landslides
Tsunamis can be generated on impact as a rapidly moving landslide mass enters the water or as water displaces behind and ahead of a rapidly moving underwater landslide. Such things that can cause such a huge landslides are Volcanic Eruptions/Collapses, Earthquakes, and Formation of Landslides on Marine Margins.
Meteorological
Meteorological conditions, such as rapidly changing barometric pressures can displace large bodies of water. These waves are not as substantial and devastating in comparison to other causes (such as earthquakes) but can still be very dangerous.
2004 Indian Ocean Earthquake and Tsunami
On December 26, 2004, a Tsunami crashed into the West Coast of Sumatra, Indonesia. The shock had a moment magnitude of 9.1 - 9.3 and a maximum Mercalli Intensity of IX (Very Violent). The undersea megathrust earthquake was caused when the Indian Plate was subducted by the Burma Plate and triggered a series of devastating tsunamis. These Tsunamis killed between 230,000 - 280,000. Indonesia was the hardest-hit country, but Sri Lanka, India, and Thailand were also hit.
Tsunami Warning Systems
The Tsunami Warning Systems have been implemented in regions with high probability of tsunamis to help citizens prepare for tsunamis and avoid mass chaos. These systems help citizens evacuate to decrease the damage done by the tsunami. The Pacific Tsunami Warning System (based in Honolulu, Hawaii) monitors tsunami and seismic activity around the world, and have saved hundreds of thousands of lives in the process.
Sources
- https://en.wikipedia.org/wiki/Tsunami
- https://en.wikipedia.org/wiki/Pacific_Tsunami_Warning_Center
- https://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunami
- https://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquake_and_tsunami
- https://en.wikipedia.org/wiki/Meteotsunami
- https://www2.usgs.gov/faq/categories/9752/3101%20