Unlike usual tsunamis, which originate from tectonic activity and the raising or lowering of the sea floor, known mega tsunamis have originated from large scale landslides or impact events.

A mega tsunami is meant to refer to a tsunami with an initial wave amplitude (wave height) measured in several tens, hundreds or possibly thousands of meters, potentially reaching up to about a kilometer in height.

Normal tsunamis generated at sea have a small wave height offshore, and a very long wavelength (often hundreds of kilometers long). They generally pass unnoticed at sea, forming only a slight swell usually of the order of 30 cm (12 in) above the normal sea surface. When they reach land the wave height increases dramatically as the base of the wave pushes the water column above it upwards.

Mega tsunamis can be caused by giant landslides, and asteroid impacts. Underwater earthquakes do not normally generate such large tsunamis, but landslides next to bodies of water resulting from earthquakes do, since they cause a massive amount of displacement.

In 1792, Mount Unzen in Japan erupted, causing part of the volcano to collapse into the sea. The landslide caused a mega tsunami that reached 330 ft (100 meters) high and killed 15,000 people in the local fishing villages.

A future eruption involving the Cumbre Vieja on the volcanic ocean island of La Palma, in the Canary Islands could create a mega-tsunami, if it were to catastrophically slide into the ocean. It could also generate a wave with an initial height of about 1,000 meters (3,281 ft) at the island, and a likely height of around 50 meters (164 ft) at the Caribbean and the Eastern North American seaboard when it runs ashore eight or more hours later.

All Vivos shelters will be located in high, mountainous terrain, providing the benefit of elevation, as well as the opportunity for immediate runoff of any water deposits, versus being buried below a permanent new body of water.

To help resist this form of catastrophe, the Vivos shelters are designed to withstand:

• Flooding submersion for extended periods