Evidence of collapsing volcanoes that cause the greatest tsunami in history

Scientists working in West Africa and the Cape Verde Islands have discovered evidence of the biggest super tsunami in human history.

Volcanic collapse created the largest tsunami in human history

They said an unexpectedly collapsing volcano about 73,000 years ago created a wave of nearly 244 meters, engulfing an island more than 48km away.

Scientists also warned that the collapse of volcanoes could cause far more damage than previously calculated.

Recent research published on the Science Advances magazine has revived the debate about whether unexpected collapses at volcanic islands or remote continental coasts could cause disaster. .

'Our view is that volcanic collapse can happen very quickly and cause serious consequences, thus potentially causing tsunami waves , " said Ricardo Ramalho, researcher. at the Lamont-Doherty Earth Observatory, Columbia University, said.

The collapse took place about 73,000 years ago at Fogo volcano , one of the largest and most powerful volcanoes in the world.

The western slopes of Fogo volcano suffered severe landslides, possibly causing a super tsunami.(Photo: NASA).

Today, this volcano has a height of 2,829 m above sea level and erupts about every 20 years, most recently in the autumn of last year.

Santiago Island, where the tsunami struck, is now home to some 250,000 people.

There is no disagreement around which volcanic slopes can pose a serious danger; At least eight smaller-scale landslides have occurred in Alaska, Japan and other parts of the world over the past few hundred years, and some have created dangerous tsunamis.

However, many scientists doubt whether large volcanoes may collapse abruptly in this new study. Instead, they think there will be periodic landslides, creating smaller tsunamis.

A study in France in 2011 also examined the fall of the Fogo volcano and claimed that the incident occurred between 124,000 and 65,000 years ago; But this study suggests that the mountain slopes include many different erosion periods.

French researchers estimate that collapsing volcanic waves only reach a height of nearly 14 meters - but this height is also enough to cause serious damage.

Several previous studies have suggested the accompanying volcanic and super-tsunami collapses that occurred in much larger prehistoric times, in the Hawaiian Islands, Mount Etna in Italy, and Indian Reunion Island. Ocean However, analysts say these examples are limited with too little supportive evidence.

The new study provides an example, which says that the estimated 160 km of rock that Fogo lost during the mountain slump collapsed at the same time, creating a wave of 244m high.

For comparison, look back at the largest tsunami that happened recently, devastating the Indian Ocean coast in 2004 and eastern Japan in 2011. The wave height in these tsunamis is only about 30m, and made from earthquake earthquakes, not collapsed volcanoes.

Santiago Island is 55km from Fogo. A few years ago, Ramalho and his colleagues working in Santiago discovered unusual rocks deep inland more than 600m and nearly 200m above sea level.

Some rocks are about the same size as trucks, and are completely different from the young volcanic environment around them. These rocks are similar to the rocks located on the island's coast: limestone, pebbles and sea basalt. Some rocks weigh up to 770 tons.

The only practical explanation scientists can make is that a large tsunami is more likely to separate them from the coast and lift them up. They calculated the size of the wave based on the energy needed to accomplish this.

To determine the timing of the event, in the laboratory, Ramalho and chemist at the center of Lamont-Doherty Gisela Winckler measured the isotopes of the helium element that exists near the surface of these rocks. . These isotopes vary according to the time the stone is exposed to the environment and cosmic rays.

The analysis showed that this time was about 73,000 years - completely within the expected range of French research.

The cliffs form from Fogo volcano.(Photo: Columbia University).

Tsunami expert Bill McGuire, an emeritus professor at the University of London who did not participate in the study, said the study 'provided convincing evidence of the formation of a tsunami, and confirmed that volcanism can crash with extremely fast speed ".

Based on their own research, McGuire says these tsunami battles can only happen once every 10,000 years.

Mr. Ramalho notes that the results of this study do not mean that a major volcanic collapse will surely happen here or anywhere.'This does not mean that any collapse can be disastrous. But its frequency may not be as rare as we thought. "

James Hunt, a tsunami expert from the British National Oceanographic Center who did not participate in the study, said the study showed that 'even modest landslides can cause tsunamis. with large levels at the coast of the neighboring islands ".

According to him, the question to be asked here is: 'can this cause dangerous events away from volcanic places, and this issue needs further discussion.'