New research suggests that some of the great volcanoes that have produced real catastrophes throughout history could remain active thousands of years after their first eruption . The threat that we thought was non-existent, it would not be so.
“While a supereruption can have a regional and global impact and recovery can take decades or even centuries,” says volcanologist Martin Danišík, from the University of Curtin (Australia). “Our results show that the danger does not end with supereruption and that the threat of new dangers exists for many thousands of years later.” Of course, although dangerous, subsequent eruptions would be much smaller than the initial one.
To reach this conclusion, the researchers relied on models from the Toba supereruption, which occurred almost 75,000 years ago in what is now known as Lake Toba, in Sumatra, Indonesia. What remains today is a complex caldera with a series of domes and other features, most notably the younger Tuff Tuff, representing the last major eruption at the site.
This supervolcano once expelled 2,800 km3 of hot magma , one of the largest eruptions known to date. Some scientists believe that the explosion was so massive that it triggered a “volcanic winter” that lasted a whole decade and a glacial period that could extend for a thousand years, although the details of the radioactive fallout remain highly disputed. Well, the models suggest that, after this first and colossal eruption, another one occurred in a north dome some 4,600 years later, a subsequent one in the Tuk Tuk dome 8,000 years later and a last one in a south dome 13,000 years later . Domes are circular mounds that are created during a volcano eruption when the lava that reaches the surface is so viscous that it does not flow easily.
All of these subsequent eruptions appear to have “taken advantage of the ‘cold halo'” of the original Toba magmatic system during its dormant period. “Our work thus demonstrates a significant delay between the eruption of the youngest Toba and the eruption of these domes, ” the authors write in the study published in Communications Earth & Environment . The period of calm that follows a supervolcanic eruption may therefore not be as calm as we thought.
Scientists believe that the magma was not reheated by the lava underneath, but was likely shot into the air in a subsolid state. The magma left over from Toba’s first eruption was probably “a roughly crystalline slurry that barely moved and was not eruptible,” the authors say. However, once it made its way into the domes, it appears to have been eruptible again. More research is needed to find out what exactly triggered this volatility and if something similar could happen in other supervolcanoes on our planet, such as Yellowstone in the United States.
“Learning how supervolcanoes work is important to understanding the future threat of an inevitable supereruption, which occurs approximately once every 17,000 years, ” says Danišík.
“Understanding those long periods of inactivity will determine what we look for in young active supervolcanoes to help us predict future eruptions.”
Fuente: Mucek, A.E., Danišík, M., de Silva, S.L. et al. Resurgence initiation and subsolidus eruption of cold carapace of warm magma at Toba Caldera, Sumatra. Commun Earth Environ 2, 185 (2021). https://doi.org/10.1038/s43247-021-00260-1
