The largest volcanic eruption of the last 5000 years on Earth It took place at the Cerro Blanco volcanic complex in the center of the Andes in Argentina. Analysis of volcanic ash deposits over a large area in the northwest of the country in question allowed researchers to reconstruct the dynamics and extent of this big eruption.
Cerro Blanco Volcanic Complex, located in the extreme south of the Andes erupted about 4,200 years ago. This wasn’t just any explosion event. It was the largest eruption in the last 5,000 years in the Central Volcanic Zone of the Andes.
The volume of ejected rock makes it one of the largest eruptions to have occurred during the Holocene (last 11,700 years). This was determined by a study conducted in 2019 by a Spanish and Argentine research team. Staff from various universities and scientific institutions from both countries participated in the study, led by José Luis Fernández Turiel of the CSIC Jaume Almera Institute of Earth Sciences (ICTJA-CSIC).
Located in Argentina’s Catamarca province, the Cerro Blanco Volcanic Complex was the source of extensive volcanic ash deposits still recognizable in a large region of the Andes. Its existence was known until now, but its origin was unknown..
“It was possible to confirm that the eruption at Cerro Blanco was the one that created these large Holocene ash deposits that covered a large area of Puna and neighboring areas of northwestern Argentina,” said José Luís Fernández Turiel.
Reconstruction with digital simulations
In addition, due to the presence of plant remains in the sediments adjacent to the ash layers studied, it was possible to determine by carbon 14 that the eruption took place 4,200 years ago.
Thanks to digital simulations, the transport and fall of ash has also been reconstructed. The eruption of Cerro Blanco It was explosive in nature and so intense that the ashes were scattered over an area of approximately 500,000 km.2, an area equivalent to that of Spain. In fact, the ash from this eruption was found 400 kilometers from the volcano, near the town of Santiago del Estero.
Likewise, the pyroclastic flows that occurred filled the adjacent river valleys with thick deposits of ignimbrite, reaching about 35 kilometers from Cerro Blanco. The emptying of the magma chamber caused by this eruption then caused the volcanic structure to collapse and a complex volcanic caldera to form.
“The geodynamic context of the area dictates that these are very explosive eruptions. They are rhyolitic magma eruptions with a lot of silica and a very high gas content,” said Francisco José Pérez Torrado of the Institute for Environmental Studies and Natural Resources (IUNAT-GEOVOL) at the University of Las Palmas de Gran Canaria. According to Pérez Torrado, “the eruption was not in the form of a ring that followed the rim of the caldera, but concentrated at one point on that rim, it was explosive and formed a very tall column of explosions almost 32 kilometers high According to our simulations.
The volume of ash deposited by this eruption was more than 170 km3, allowing the study’s authors to estimate that the Cerro Blanco eruption had a Volcanic Eruption Index (VEI) 7. Blanco is one of the largest volcanic events recorded in the last 10,000 years: similar to the one that occurred on the island of Santorini, which marked the end of the Minoan civilization, and the volume of magma doubles the volume of the eruption. The eruption of Tambora volcano in 1815 is an event attributed to cooling global temperatures.
Differences in the behavior of northern and southern eruptions
Fernández-Turiel added that the discovery “changes the pattern of active volcanism in the Andean region.” Until now, it was thought that everything in the Central Volcanic Zone worked exactly the same as in the southern zone: many volcanoes with many eruptions over time. What we see here is that there is very little eruption, but large volumes of magma and very high explosiveness.”.
This finding provides researchers with an excellent temporal guide to the study of the many geological, archaeological, and paleoclimatic features that occurred in the mid-Holocene over a large geographic area of South America.
According to Norma Ratto, an archaeologist at the Institute of Culture at the University of Buenos Aires, “that determined the extent and occurrence of this big bang.” provides new information to interpret different aspects of hunter-gatherer societies living in the sector. Southwest Argentina during the Holocene, for example, experienced changes in the mobility of groups due to differential occupation of areas, alteration and alteration of circulation routes that allowed connection between different ecological levels, changes in ecosystems and pre-Hispanic populations, among others.
Reference work: https://estudiosgeol.revistas.csic.es/index.php/estudiosgeol/article/view/982/1200%20
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