Liputan6.com, Jakarta – Tsunami with a height of 40 meters crashing, 2 islands immediately perished. It occurred due to the effects of the eruption of Mount Krakatoa on August 27, 1883.
Tsunamis, one of which can be triggered by volcanic eruptions. Recently, more powerful findings were reported by researchers from the Lamont-Doherty Earth Observatory, Columbia University, United States.
The traces show that about 73,000 years ago Mount Fogo collapsed in a matter of seconds. This triggered a tsunami as high as 800 feet or 243 meters that swept across Santiago Island, 48 kilometers away.
The height of the tsunami, if it occurred in Paris, could hit the top of the Eiffel Tower, which has a height of 324 meters. In fact, it is certain that the Statue of Liberty, which is only 93 meters high, could immediately sink if it happened in New York.
Currently, Mount Fogo towers as high as 2,829 meters above sea level. Meanwhile, Santiago Island, which used to be the worst affected area, is now inhabited by 250,000 people. Can’t imagine what would happen if the same thing happened today.
The incident is a long time away from the present, but the study in the journal is an alarm for us that a collapsed volcano can cause great catastrophe. In fact, bigger than ever imagined.
“What we mean is that a volcanic collapse event can occur very quickly and catastrophically. Which can trigger giant tsunami,” said Ricardo Ramalho of the Lamont-Doherty Earth Observatory, Columbia University, United States.
Fortunately, “that doesn’t happen often.” Whatever, he said, modern humans must consider the potential dangers.
On Santiago Island, 55 kilometers from Fogo, Ricardo Ramalho and his team found traces of the brunt of the waves in the form of giant boulder. Some are as big as vans, others weigh up to 770 tons.
The rock does not resemble the geological structure around it. However, it matches the seabed rock around the shoreline. Even though they are located at a location as high as 650 feet or 198 meters above sea level. How did it get carried to the top?
The only realistic explanation for the phenomenon is this: giant waves ripped the rock from the shoreline and lifted it up.
Based on the size and weight of the rock, scientists try to calculate the energy required to bring the rock from the ocean floor and predict the height of the waves.
Ramalho and geochemist Gisela Winckler then measured isotopes of the element helium embedded near the surface of the giant rock — the isotopes change depending on how long the rock has been lying out in the open, exposed to cosmic rays.
The results of the analysis refer to about 73,000 years ago. Earlier than the team of researchers from France had expected.
Tsunami expert Bill McGuire, professor emeritus at University College London who was not involved in the research, said the latest study provides strong evidence of mega-tsunami formation and confirms that when a volcano collapses instantly, such a catastrophe can occur.
Based on his understanding, McGuire said that such a mega-tsunami might occur once every 10,000 years. “Shows there is a real and serious potential danger that is owned by the ocean basin which is home to an active volcano,” he said.
Although it sounds terrible, Ricardo Ramalho hastily underlined, their findings are not a ‘sign’ that similar events will occur in the near future around Mount Fogo or in other locations.
Create a Debate
The conclusions of the researchers regarding the giant tsunami rekindled the debate as to whether volcanoes are capable of triggering mega-tsunami.
They agreed that a collapsed volcano could cause great danger. It was evident in Japan and Alaska in the past few hundred years. Some of them even triggered a deadly tsunami.
Meanwhile, some scientists doubt that a large mountain could suddenly collapse. They argue, the volcano slides in several stages — which triggers a series of small tsunamis.
Several other studies have previously mentioned that a number of volcanic collapse events in prehistoric times resulted in megatsunami. For example, in the Hawaiian islands, Mount Etna in Italy, and La Reunion Island in the Indian Ocean. However, critics say, the examples are too few and the evidence too thin.
Giant Tsunami Trail
Although it caused destruction and claimed the lives of many people, the tsunami in Aceh in 2004 which killed around 230,000 people and the giant wave that hit Japan in 2011 were not categorized as ‘mega-tsunami’. Because the wave height is ‘only’ about 30 meters. The cause was an underwater earthquake, not a volcanic one.
Researchers claim to have found traces of a 50-meter-high tsunami triggered by the activity of Mount Etna in Italy — which 6 square miles of rock collapsed — about 8,000 years ago.
Meanwhile, the Lituya Bay megatsunami occurred on July 9, 1958. At that time, an earthquake measuring 8.3 on the Richter scale triggered a landslide that caused 30 million cubic meters of rock and ice from high cliffs, dropping into the water.
After that a wave as high as 524 meters was formed. Millions of trees fell and were swept away by the flood. It was the highest wave ever known to man. The disaster killed 5 people. The affected area is remote from the area that is crowded with humans.
In 2011, French scientists also studied the collapse of Mount Fogo, saying that the event occurred 124,000 to 65,000 years ago. But the study also said, it happened not only once. French researchers estimate, the waves triggered ‘only’ about 45 feet or 13 meters.
On the other hand, recent studies estimate that the 800 feet or 243 meter tsunami caused by the collapsed Mount Fogo was caused by 160 cubic kilometers of rock being dropped all at once.