Mega tsunamis have different features from each other and are caused by underwater tectonic activity (movement of the earth's plates). It occurs along the plate boundaries and displaced by water is produced due to earthquake and the rise and fall in the sea floor.
Scientists and researchers found an evidence which made them believed that 73,000 years ago, an 800-foot tsunami that surged across the Atlantic Ocean was triggered due to partial collapsed of the Fogo Volcano.
Nature World News writes a report, that the Fogo still stands 9,300 feet or 2,829 meters above sea level including the recent eruption last year. The remaining cone of the volcano after the collapse, says that the Fogo was once massive, as the collapse created towering waves.
On the contrary, Ricardo Ramalho, a researcher at Columbia University's Lamont-Doherty Earth Observatory, found out an unusually large and old boulder nearly 650 feet above sea level and 2,000 feet inland.
Ramalho and his colleagues came up with possibilities that the boulders were originated from similar rocks bordering the island and was transported via a large wave to the landscape. In order for this kind of wave to carry the boulders-some weighing as much as 770 tons-researchers have estimated of an 800 ft mega tsunami was able to make it.
He added in a statement, that flank collapses can happen in an extremely fast and in a catastrophic manner, which are able to trigger giant and even mega tsunamis. However, they probably don't happen very often, but it needs to be taken into account when it comes to the hazardous potential these kind of volcanic features could produce.
One mega tsunami was recorded in 1958, the largest recorded wave-measuring 1,724 feet - surged across the uppermost corner of Alaska. However, two fishermen aboard their vessel and were carried over a forest by the wave, but managed to come through the event without any injury.
"The study provides a robust evidence of mega tsunami formation and confirms that when volcanoes collapse, they can do extremely rapidly," said Bill McGuire, a tsunami expert from the University College London.
