The eruptions of the supervolcano have caused some of the greatest catastrophes in the history of our planet, however, we still do not know how to predict when or how they will attack.
Instead of falling into a period of quiet recovery, new research suggests that some of these large volcanoes may remain active for thousands of years after their initial eruption, posing a threat for much longer than we thought.
At times, the supervolcano could even be “quiet” for thousands of years before acting again briefly. These subsequent eruptions are much smaller than the initial explosion, but still pose a danger.
“While a supereruption can have a regional and global impact and recovery can take decades or even centuries,” says volcanologist Martin Danišík of Curtin University in Australia, “our results show that the danger is not it has ended the super-eruption and the threat of there being more dangers for many thousands of years. “
The findings are based on models of the Toba supereruption, which occurred nearly 75,000 years ago in what is now known as Lake Toba in Sumatra, Indonesia. What remains today is a complex boiler with a few domes and other elements, among which stands out the younger Toba Toba, which represents the last great eruption of the place.
At that time, this supervolcano blew approximately 2,800 km3 of hot magma in the air: one of the largest eruptions known to date. Some scientists think the explosion was so massive that it caused a ten-year “volcanic winter” and a glacial period that may have lasted a thousand years, although the details of the consequences are still hotly debated.
Now, it appears that the recovery phase of the volcano, technically known as resurgence, is also in conflict. The period of calm that occurs after a supervolcanic eruption may not be as quiet.
“The findings challenge existing knowledge and the study of eruptions, which usually involves searching for liquid magma under a volcano to assess future danger,” Danišík explains.
But the liquid magma beneath Toba does not appear to have stagnated for long after the initial eruption. Instead, as the floor of the boiler cooled, he squeezed the remaining magma up and up along the fault lines, with a “hood” at the top that Danišík compares to a shell. of turtle.
The finding is based on two proxies: the minerals feldspar and zircon, which contain a time stamp for volcanic gases, such as argon and helium. These proxies were measured from samples of volcanic rock taken from the Toba caldera, to see if their latency period caused eruptions.
When researchers used the resulting geochronological data and connected them to thermal modeling, they found multiple episodes of feldspar and zircon, and these eruptions separated about 13.6,000 years ago.
Ultimately, the models suggest that a dome north of the caldera erupted about 4,600,000 years after the initial and colossal eruption, while the Tuk Tuk dome toward the center erupted after a delay of 8,000. years, while a dome to the south then erupted a delay of 13,000 years.
All of these subsequent eruptions appear to have “taken advantage of the” cold halo “of the original Toba magma system during its latent period.
“Our work thus demonstrates a significant delay between the eruption of younger Toba Toba and the eruption of these domes,” the authors write.
“We propose that the eruptions of the domes indicate the appearance of a resurgence of uplift and an associated opening of pathways to the surface through which plugs and dikes of remaining solidified conduits were extruded to the surface to invade the magma that acts like the plunger of a syringe “.
Although these domes kept magma cooled for thousands of years, the material was not fresh enough to withstand the eruption.
The magma was not reheated by the lava below, but probably fired into the air in a subsoil state. In light of the findings, the authors argue that we need to re-evaluate our concept of what is actually “eruptable”.
According to the authors, the magma remaining after the initial eruption of Toba was probably “a thick crystalline mushroom that was barely mobile and not eruptive.”
However, once it entered the domes, it appears to have erupted again. More research is needed to find out exactly what triggered this volatility and whether something similar could happen to other supervolcanoes on our planet, such as Yellowstone.
Given how little we know about supervolcanoes in general, the suggestion that the Toba supervolcano continued to cause smaller magma episodes during its resurgence period will no doubt continue to be discussed for years to come.
There could be rest for volcanoes, but not for volcanologists.
“Learning how supervolcanoes work is important to understanding the future threat of an inevitable super-eruption, which happens about once every 17,000 years,” Danišík says.
“Understanding these long latent periods will determine what we look for in active young supervolcanoes to help us predict future eruptions.”
The study was published in Earth and Environment Communications.