How is a megatsunami generated?

A megatsunami is an extremely large wave created when a substantial and sudden volume of material falls into or near a body of water. Unlike ordinary tsunamis caused by tectonic plate movements, megatsunamis are splashed upwards and outwards by events like massive landslides, volcanic eruptions, or meteor impacts. These giant waves can feature initial heights in the hundreds of metres.

What we know

• Megatsunamis are created by a substantial and sudden displacement of material into a body of water, unlike ordinary tsunamis that stem from underwater tectonic activity. [1, 2]
• Unlike ordinary tsunamis caused by underwater tectonic activity, megatsunamis result from events such as landslides, meteor impacts, or volcanic eruptions near water. [2]
• Initial wave heights for megatsunamis can reach hundreds of metres because the water is splashed upwards and outwards by the displacement. [2]
• Examples of events causing megatsunamis include the 1958 Lituya Bay landslide and the 1883 volcanic eruption of Krakatoa. [2]

Still open

• Researchers debate whether a potential collapse at the Cumbre Vieja volcano would retain significant tsunami size far away from La Palma or if wave height would quickly decay.

Where to go next

• a case in pointWhat caused the Lituya Bay megatsunami?
• compared withHow do tectonic earthquakes create ordinary tsunamis?
• what caused itCould a volcano collapse trigger an Atlantic megatsunami?
• the bigger pictureWhat is a seiche wave?
• whoHow did François-Alphonse Forel study lake oscillations?
• an unexpected connectionHow are alpine lake oscillations linked to dry beaches?The scientific term seiche originates from a Swiss French dialect word derived from the Latin for dry, describing how water recedes during the oscillation.

Sources

• [1]megatsunami (Wikidata Q583313) · CC0 1.0
• [2]Megatsunami · CC BY-SA 4.0
• [3]Cumbre Vieja tsunami hazard · CC BY-SA 4.0
• [4]Seiche · CC BY-SA 4.0
• [5]Tsunami · CC BY-SA 4.0