Mysterious Source of Huge 200-Year-Old Volcanic Eruption Finally Revealed

Researchers have identified the source of a huge volcanic eruption that posed a mystery for nearly 200 years, a study reports. The event, which took place in 1831, was one of the largest eruptions of the 19th century and resulted in significant climate cooling of around one degree Celsius in the Northern Hemisphere over the course of the subsequent years. This cooling is thought to have contributed to widespread crop failures and devastating famines in some regions. But despite the catastrophic effects of the eruption, the identity of the volcano responsible had long been the subject of significant debate. Now a team of researchers say they have identified the volcano responsible in a study published in the journal Proceedings of the National Academy of Sciences. The team used evidence from well-dated ice cores and other geological records to pinpoint the Zavaritskii caldera— an “extremely remote” volcano situated on the uninhabited island of Simushir in the Kuril Islands chain—as the source of the 1831 eruption. The Kuril Islands are a volcanic archipelago stretching across more than 800 miles of the northwest Pacific between Hokkaido, the northernmost of Japan’s main islands, and the Kamchatka Peninsula in Russia’s Far East. The Kuril chain is controlled by Russia, although Japan claims some of the southernmost islands. The latest study involved an analysis of polar ice core records that were found to contain ash deposits from the 1831 eruption. These records are long cylinders of ice drilled from the thick ice sheets in polar regions. They essentially function as time capsules, preserving detailed information about Earth’s climate and environment over hundreds of thousands of years. “Only in recent years have we developed the ability to extract microscopic ash shards from polar ice cores and conduct detailed chemical analyses on them, “study lead author William Hutchison, with the School of Earth and Environmental Science at the University of St. Andrews in the United Kingdom, said in a statement. He added: “These shards are incredibly minute, roughly one-tenth the diameter of a human hair.” Analysis of the ash deposits revealed a “perfect fingerprint match” that enabled Hutchison and colleagues to tie the 1831 eruption with the Zavaritskii volcano. “We analyzed the chemistry of the ice at a very high temporal resolution. This allowed us to pinpoint the precise timing of the eruption to spring-summer 1831, confirm that it was highly explosive, and then extract the tiny shards of ash. Finding the match took a long time and required extensive collaboration with colleagues from Japan and Russia, who sent us samples collected from these remote volcanoes decades ago,” Hutchison said. “The moment in the lab when we analyzed the two ashes together, one from the volcano and one from the ice core, was a genuine eureka moment. I couldn’t believe the numbers were identical. After this, I spent a lot of time delving into the age and size of the eruption in Kuril records to truly convince myself that the match was real.” The researchers then reconstructed the eruption’s magnitude and “radiative forcing”—the effects of volcanic gases and particles on sunlight and heat—to show that the event could account for the climate cooling observed in the period 1831–1833. Stock image: A volcano erupting on Chirpoy Island, which is located close to Simushir in the Kuril Islands archipelago, Russia. A volcano on Simushir (not pictured) has been identified as the source of a “mystery”… Stock image: A volcano erupting on Chirpoy Island, which is located close to Simushir in the Kuril Islands archipelago, Russia. A volcano on Simushir (not pictured) has been identified as the source of a “mystery” 19th century eruption. Nicolas Tolstoï/iStock/Getty Images Plus “These data provide a compelling candidate for this large-magnitude mystery eruption and demonstrate the climate-changing potential of these remote yet highly significant Kuril Island volcanoes,” the authors wrote in the study. The study highlights the importance of investigating the sources of “mystery” eruptions, because they can provide new insights into where climate-altering volcanic events might occur. “There are so many volcanoes like this, which highlights how difficult it will be to predict when or where the next large-magnitude eruption might occur,” Hutchison said. “As scientists and as a society, we need to consider how to coordinate an international response when the next large eruption, like the one in 1831, happens.” Do you have a tip on a science story that Newsweek should be covering? Do you have a question about geology? Let us know via science@newsweek.com. Reference Hutchison, W., Sugden, P., Burke, A., Abbott, P., Ponomareva, V. V., Dirksen, O., Portnyagin, M. V., MacInnes, B., Bourgeois, J., Fitzhugh, B., Verkerk, M., Aubry, T. J., Engwell, S. L., Svensson, A., Chellman, N. J., McConnell, J. R., Davies, S., Sigl, M., & Plunkett, G. (2024). The 1831 CE mystery eruption identified as Zavaritskii caldera, Simushir Island (Kurils). Proceedings of the National Academy of Sciences, 122(1). https://doi.org/10.1073/pnas.2416699122