A tsunami is a massive wave which is created by the displacement of large amounts of water within the ocean, usually by an underwater earthquake. While the wave amplitude on the open ocean is fairly low, the waves increase massively in height when they approach the coast and channel large amounts of water in small areas, causing waves with a height of dozens of meters or more.
Survivors recount that one of the more ominous aspects of an approaching wave is the way the sea seems to disappear before it approaches - sometimes this phenomenon gave those who understood what it meant enough warning to save themselves from the coming flood.
The tsunami also goes by the (rather inaccurate) English name of Tidal Wave.
- 1958 Lituya Bay megatsunami - the largest wave ever recorded, with a height of 524 meters (250 feet taller than the Empire State Building.
- 2004 Indian Ocean tsunami - the tsunami that caused the largest recorded loss of life.
- News: Ancient tsunami 'hit New York'
- News: Farang ghosts haunt local Thais in Phuket, Phi Phi, Khao Lak - tsunamis can cause ghosts as well.
- Event/News: Magnitude 7.0 Earthquake Hits Northern Japan
- News: Rescuing A Potential Nuke From The Chile Quake - how a tsunami can complicate a mission indirectly
Game and Story Use
- Tsunamis are great for wiping out inconvenient coastal towns and cities and turning them into half-submerged ruins filled with treasure to loot.
- Tsunamis are a great challenge for a superhero team - how can they either rescue as many people as possible from it or stop it entirely? Since the earthquake is likely detected before the wave, they have a short time for preparation - but not much.
- Summoning a Tsunami may be (part of) the BBEG's plan - whether using his own magic, the power of Cthulhu or an artifact of doom.
- A tsunami is noticable, but not all that dangerous, out at sea - PCs on a ship may detect one significantly before it reaches land and, if equipped with radios (or equivalent technology) might get a chance to send a signal.
- Tsunamis have a tendency to wash all kinds of things out to sea. Including, perhaps, PCs.
- "You all meet in a seafront tavern" and then "Just as you have decided that, a man comes running in from outside, shouting that the sea has vanished…"