In 1831 the sky darkened and the Sun turned blue. We had been wondering for years which volcano was responsible

Throughout human history, there are many chronicles of large volcanic eruptions, some capable of sinking entire cities under ashes, others capable of causing temporary changes in the climate of entire hemispheres.

What happened in the summer of 1831 was closer to the latter: the eruption of a volcano cooled the global climate by approximately 1º Celsius by covering the sky with sulfur gas emissions. The summer days became sullen and even making the color of the sun turn bluish or greenish.

The impacts went beyond the meteorological: crops were affected by the lower intensity of sunlight reaching the surface. This in turn has been related to famines that occurred in the first half of the 1830s in countries such as India and Japan.

We knew that a volcano was responsible for this strange atmospheric phenomenon, but historiographic records do not speak of any eruption of considerable magnitude during that summer. So what was the volcano responsible for this dark summer?

For decades, scientists have tried to figure out which volcano was responsible for this strange event. In recent years, various volcanoes have been identified as possible responsiblesuch as the Babuyan Claro in the Philippine Islands, or the Ferdinandeaan underwater volcano located about 30 km south of the coast of Sicily.

Now an international team of researchers has found the likely culprit behind the powerful 1831 eruption: Zavaritsky volcanolocated on the island of Simushir, in the Kuril Islands archipelago.

How did they discover it? The discovery is the result of the analysis of the ice extracted from the poles. The ice cores They are cylindrical samples that cross various ice strata, each one associated with different years, events or eras. Ash and smoke from large volcanic eruptions can travel thousands of kilometers in the atmosphere and, remember, this eruption reached the skies of Europe.

The team managed to find tiny ash crystals in the ice core (we are talking about fragments with a diameter approximately equivalent to one tenth of the diameter of a human hair) and carry out chemical analyzes of them. By studying these fragments found in the ice, they discovered that their chemical composition was the same as that of the ash deposits found in the Zavaritskii volcano itself.

Eureka moment

“The moment in the laboratory in which we analyzed the two ashes at the same time, one from the volcano and the other from the ice core, was a real eureka moment. I couldn’t believe the numbers were identical. After this, I spent a lot of time digging into the age and size of the eruption in the Kuril records to convince myself that the link was real,” explained in a press release Will Hutchison, co-author of the study.

Details of the analysis were published in an article in the magazine Proceedings of the National Academy of Sciences (PNAS).

We still do not have the ability to accurately predict volcanic eruptions. In the case of small volcanoes this is a local problem that affects, often drastically, the people who live nearby; But in the case of some volcanoes, the consequences can reach the entire planet even in a milder way.

“There are so many volcanoes like this, which highlights how difficult it will be to predict when or where the next large eruption will occur,” Hutchison added.. “As scientists and as a society, we have to consider how to coordinate an international response when the next major eruption, like that of 1831, happens.”

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Images | Oleg Dirksen