It has finally been resolved an enigma that has lasted almost 200 years. A research team, led by researchers fromUniversity of St. Andrews in the United Kingdom, would have identified the source of the volcanic eruption which, in 1831during the “Little Ice Age”, caused a global drop in temperatures of up to 1°Ctriggering climate changes that led to crop failures and famines in several regions of Asia. The volcano responsible is the Zavaritski caldera, located on the remote island of Simushir off the coast of the island of Hokkaidoin the’Pacific Oceaninside theKuril archipelagopart of Belt of Fire. In 1831, it would produce a powerful explosive eruption with a magnitude of 5.5 VEHICLE (Volcanic Explosivity Index).
The catastrophic event: what happened after the 1831 eruption
The historical period between 1800 and 1850 it is known as the “Little Ice Age”. This was the coldest period in the last 500 years and was caused by the succession of several explosive volcanic events. Among these, the eruption of the volcano Tambora in Indonesia In the 1815 and that of Cosegueina in Nicaragua In the 1835.
For over 200 years scientists have tried to find the person responsible for the volcanic eruption that, in the summer of 1831, disrupted the global climatecausing temperatures to drop between 0.5 and 1 °C, as well as responsible for a decrease in monsoon rainfall in Africa and India. Beyond 13 million metric tons of volcanic pyroclastic material and sulfides were released into the atmosphere, blocking the passage of solar radiation towards the ground and triggering, among the consequences, a famine which struck India And Japan between 1832 and 1838, both victims of adverse weather conditions and of poor harvests. The same succession of events could then have contributed to the intensification and/or spread of Asian choleraspread from India, Japan and China to Europe from 1826 until 1837.
In that year, the German composer Felix Mendelssohntraveling through the Alps, wrote: “It’s as cold as in winter, there is already thick snow on the nearby hills.” Other historical documents report sightings of a sun with unusual colors – green, viola or blue – observed in several areas of the northern hemisphere. Similar phenomena are known, for example, after theeruption of the Krakatoa volcano in Indonesia in 1883and are caused by the scattering and absorption of solar radiation within dense volcanic aerosols.
What the new study says
For many years, there were two main suspects: the volcano Babuyan Claroin Philippinesand theFerdinandea Islandlocated 50 km south of the Agrigento coast, whose formation dates back to the summer of 1831. However, a new study published in PNAS (Proceedings of the National Academy of Sciences) ruled out both hypotheses, tracing the true origin of the eruption to Zavaritski caldera, a remote volcano located onSimushir Islandpart of the archipelago of Kuril Islandsin the Pacific Northwest, between the island of Hokkaido and from Kamchatka Peninsula.
“For many terrestrial volcanoes, especially those in remote areas, we have little information regarding historical eruptions“he declared Will Hutchisonstudy co-author and volcanologist at the University of St. Andrews in Scotland. “No one lives on Simushir Island, and historical records are limited to a handful of ship logs that passed by every few years.“
Analyzing the concentration of volcanic ash in some ice cores from the Greenlandscientists have identified high concentrations of cryptotephraincredibly minute fragments of volcanic glass, with a diameter of about a tenth of that of a human hair, dating back to the summer of 1831. Furthermore, a high quantity of sulfur produced by atmospheric fallout was found, more than 6.5 times compared to levels found for the same period in Antarctic ice cores. This evidence demonstrated that the eruption must have occurred in the Northern Hemisphere, therefore closer to Greenland than to Antarctica.
THE’chemical analysis of the volcanic material showed a perfect correspondence with samples from the Kuril archipelago. The eruption would have occurred close enough to Japan to cause crop destruction, but far enough away from go unnoticed by the population. Finally, the radiocarbon dating and the comparison with samples taken from different islands in the Kuril archipelago made it possible to precisely identify the Zavaritski volcano, which, in that period, gave rise to an eruption highly explosivewith an index VEI between 5 and 6, solving it like this a mystery that had lasted for almost 200 years.
