| Science
A gigantic collapse of the eastern flank of the island of Fogo, one of the highest and active oceanic volcanoes, caused about 73,000 years a sea wave with a dimension greater than 200 meters.
A wave that gave rise to a “mega-tsunami”, which owes their training to slip a volcanic walls of the existing volcano on Fogo Island in Cape Verde.
The study now given to know was done by researchers Ricardo S. Ramalho, Gisela Winckler, Joseph Wood, George R . Helffrich, Ana Hipólito, Rui Quartau, Katherine Adena and Joerg M. Schaefer.
The tests were on Friday made known through the Science Advances , a new magazine Science publishing group.
online RTP talked to one of the researchers of this geological phenomenon, which tells us how the whole process unfolded.
The study geological volcanic deposits in the archipelago of Cape Verde, began to be realized in 2010, on May Island, the research team led by Professor José Madeira, the Geology Department of the Faculty of Sciences of Lisbon.
The research group discovered during field analysis, an area where they were “foreign deposits.”
A area in question had all the features of being formed by a tsunami. Very destintas characteristics of other deposits linked to geological phenomena.
geological material deposits which Professor Joseph Wood called the collapse of one of the side walls of the east side of the island of Fogo.
“It is a wave that, if we use a local reference, which everyone knows, almost cover the pillars of the bridge on April 25th.”
To confirm this origin on the island May, the investigator went to the island of Santiago in 2011, and found deposits of volcanic materials in areas higher than the ones on the island of May.
that proves the theory of the formation of a “mega-tsunami”, during the slipping of volcanic wall, which dragged the material to great distance.
Foi also at this time that Professor Joseph Wood met a colleague, that you unveiled the existence of more deposited material located in even higher place on the island of Santiago.
This phenomenon, according to investigators, took place about 73,000 years, when the slip of one of the walls of the Fogo volcano have given rise to a “mega-tsunami”.
The investigator José Madeira states that the Fire Island volcano is very steep, with a height to currently be around three thousand meters. It has conducive features to slips magmatic walls.
At the time of the slip now studied and confirmed the existence of deposits, the volcano would be approximately 2,200 meters, ie a much lower height.
For the researcher, future sliding or slipping is not set aside, being totally unpredictable when that will happen.
The evidence on the ground documenting the impact of waves up to at least 170 meters above current sea level that deposited volcanic material on Santiago Island, 55 kilometers east of Fire Island.
“It’s a wave that if we use a local reference, which everyone knows, almost cover the pillars of the Ponte 25 de Abril. “
Graphics: Sara Maguey – RTP
This study rekindles debate that has lasted for decades about whether the gravitational collapses of volcanic islands, which occur suddenly and a catastrophic way, and are large tsunamis generators.
The study thus establishes a causal link between deposits found in Santiago fire and collapse, indicating that this has occurred in a catastrophic manner and produced a huge tsunami.
“Part of the La Palma Island may collapse catastrophically and generate a large tsunami. This tsunami was modeled and modeling gives the waves near the source area with completely astronomical heights of 400, 600, 800 meters. “
Once the sea level stood about 50 meters lower than the current, it can be inferred that the tsunami flooded the coast of the island of Santiago, reaching some sites that were the altitudes and greater than 270 meters .
One of the studies of this phenomenon is also bringing to light the issue of how to place these slips:. if they are masses of single material or are partial landslides
Important factors that, according to the researcher FCUL Joseph Wood, cause consequences for the formation of very different tsunamis.
Um of examples of possible volcanic formation that will cause a “Dantesque” tidal wave is the volcano on the island of “La Palma”, in the Canaries, which is being accompanied by a team of scientists to care Geologist Simon Day and Steven Ward.
“A part of La Palma Island may collapse catastrophically and generate a large tsunami. This tsunami was modeled, and modeling gives waves in near the source area with completely astronomical heights of 400, 600, 800 meters, (…) although considered fanciful, (…) is now no doubt that these waves can be formed and can reach dimensions abysmal. “
The island of Fogo currently rises 2,829 meters above sea level and runs average erupting every 20 years.
The most recent activity occurred between November 2014 and February this year, having reached several villages which dwelt on the volcanic rim.
The currently active volcano was rebuilt within the scar of collapse created for 73,000 years, being so tall and steep as the previous volcano .
The potential energy to further collapse of large continues to exist, so it is essential to remain vigilant.
This finding, the researchers said, warning again to the potential danger of lateral collapses of volcanic islands and the need for society to enhance their resilience to threats of this type.
Becoming so necessary to deepen knowledge about what triggers these volcanic collapses, as they occur and how to produce giant tsunamis, and what is the capacity of these waves to reach distant shores.
The researchers also say it is necessary to strengthen the monitoring capabilities.
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