Less than 4,000 years ago, Antarctica was hit by what’s thought to be the largest volcanic eruption on the continent since the last Ice Age.
Scientists say the massive event launched roughly as much rock and ash as the eruption of Indonesia’s Mount Tambora in 1815, which killed nearly 90,000 people and brought on what’s become known as ‘the year without summer.’
While it was previously thought the explosive event happened as far back as 8,300 years ago, a new study suggests it was much more recent, and gave rise to one of Antarctica’s most active calderas.
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Scientists say the massive event launched roughly as much rock and ash as the eruption of Indonesia’s Mount Tambora in 1815, which killed nearly 90,000 people and brought on what’s become known as ‘the year without summer.’ It created a depression nearly 6 miles wide
The Deception Island eruption 3,980 years ago caused the upper part of the volcano to collapse suddenly, creating a depression nearly 6 miles wide (10km).
This is what gives the island its characteristic horseshoe shape.
Though the researchers originally set out to explore the climatic history of the region, unexpected findings in the sediment cores prompted them to further investigate the island’s deposits.
‘The initial objective of the study was purely climatic, since we wanted to reconstruct the climate fluctuations of this region for the last 11,700 years using different proxies found in the sediments of the Byers Peninsula lakes, about 40 kilometers north of Deception Island,’ says co-author Sergi Pla, researcher at CREAF.
‘However, the presence of a different sediment layer in all lakes and of the same age after a thick layer of tephra surprised us.’
The team studied sediment core samples extracted during the HOLOANTAR project, between 2012 and 2014.
The sediments suggest the area experienced an eruption 3,980 years ago.
When the magna chamber emptied, the sudden pressure drop and resulting collapse spurred a seismic event that was recorded in sediments at the bottom of 4 lakes in Antarctica’s Byers Peninsula.
Less than 4,000 years ago, Antarctica was hit by what’s thought to be the largest volcanic eruption on the continent since the last Ice Age. The team studied sediment core samples extracted during the HOLOANTAR project, between 2012 and 2014
‘Later geochemical and biological analyses indicated us that these sediments had terrestrial origin and were deposited abruptly in the lake’s bottom,’ said Santiago Giralt, researcher at ICTJA-CSIC.
‘These results suggested the occurrence of a major earthquake that affected all this area; put us on the track that, perhaps, we were not facing a common earthquake but the one generated by the collapse of the caldera of the Deception Island volcano.
‘From here on, we pulled the thread.’
The team was able to narrow down the date of the eruption through several geochemical, petrological, and paleolimnological techniques conducted on the sediment cores.
When the magna chamber emptied, the sudden pressure drop and resulting collapse spurred a seismic event that was recorded in sediments at the bottom of 4 lakes in Antarctica’s Byers Peninsula (yellow star in map above)
‘The recovered sedimentary records showed a common pattern: first the volcanic ash from Deception Island eruption, overlaid by a sediment layer almost one meter thick composed by material dragged from the lakes’ shoes to their bottom due to the large earthquake and, finally, the common lake sediments, which are characterized by an alternation of clays and mosses,’ Giralt says.
‘Using this methodology, we were able to estimate the depth of all studied samples and to determine if they were part of the same magma and eruptive episode,’ said Antonio Álvarez Valero, researcher from the University of Salamanca (USAL) and co-author of this study.
The Deception Island caldera is one of Antarctica’s most active, and has birthed over 20 eruptions in the last 200 years.
HOW CAN RESEARCHERS PREDICT VOLCANIC ERUPTIONS?
According to Eric Dunham, an associate professor of Stanford University’s School of Earth, energy and Environmental Sciences, ‘Volcanoes are complicated and there is currently no universally applicable means of predicting eruption. In all likelihood, there never will be.’
However, there are indicators of increased volcanic activity, which researchers can use to help predict volcanic eruptions.
Researchers can track indicators such as:
- Volcanic infrasound: When the lava lake rises up in the crater of an open vent volcano, a sign of a potential eruption, the pitch or frequency of the sounds generated by the magma tends to increase.
- Seismic activity: Ahead of an eruption, seismic activity in the form of small earthquakes and tremors almost always increases as magma moves through the volcano’s ‘plumbing system’.
- Gas emissions: As magma nears the surface and pressure decreases, gases escape. Sulfur dioxide is one of the main components of volcanic gases, and increasing amounts of it are a sign of increasing amounts of magma near the surface of a volcano.
- Ground deformation: Changes to a volcano’s ground surface (volcano deformation) appear as swelling, sinking, or cracking, which can be caused by magma, gas, or other fluids (usually water) moving underground or by movements in the Earth’s crust due to motion along fault lines. Swelling of a volcano cans signal that magma has accumulated near the surface.
Source: United States Geological Survey
But, the episode 4,000 years ago may be its most extreme to take place in the current geological epoch.
‘The colossal episode of eruptive caldera collapse ejected between 30 and 60 cubic kilometers of ash, comparable in volume to the eruption of the Tambora volcano in 1815, an event that is attributed to a global temperature cooling that resulted in a series of bad harvests in Europe, in what is known as the “year without summer,”’ explains Adelina Geyer, ICTJA-CSIC researcher and co-author of the study.
‘It is very important to be able to date the type of eruptions that allow us to understand the climatic changes caused by volcanic eruptions, in this particular case at high austral latitudes.’