Researchers have found evidence that suggests a massive volcano collapse off the coast of Africa caused an 800-foot-high megatsunami that covered present-day Santiago Island.

Imagine a tsunami up to 800 feet high—its size and strength ultimately submerging an island over 30 miles away. 
According to researchers, the Fogo volcano swiftly collapsed and caused exactly that about 73,000 years ago.
To gauge the extent of the megatsunami, the team took stock of bizarre boulder formations on Santiago Island, 34 miles away from the Fogo volcano. 
Those boulders didn't comport with the geology of the island itself, but instead appeared to have been moved from the shore and placed inland. 
The size of the wave was determined