Abandoned Soviet Island Contained Quadruple Volcanoes That Caused a Violent Eruption in 1831

For almost two decades, experts puzzled over a strange and sudden drop in global temperatures that occurred in 1831. The mysterious cooling, which disrupted weather patterns and crop yields, had long been linked to a huge volcanic eruption, yet the exact source remained elusive. The search spanned continents, but no known volcano fits in the picture. Until now. In a stunning revelation, a team of international experts has traced the 1831 climate-altering eruption to an unlikely source: a long-forgotten Soviet military island hidden deep within the North Pacific. This eruption did not come from a single peak but from one of the four towering volcanoes on Simushir Island, part of the disputed Kuril archipelago, as per Gizmodo.

This remote, eight-kilometer-long landmass, which was once used by the USSR as a secret nuclear submarine base, harbors four huge volcanic peaks: Milna, Zavaritski, Prevo, and Uratman, arranged in a near-perfect row visible even from space. And it was Zavaritski, the seemingly modest 2,047-foot (624-meter) volcano at the center of this chain, that cooled half of the world. Volcanologist William Hutchison remarked, “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,” as per Gizmodo.

The expert team’s findings were published in the Proceedings of the National Academy of Sciences, matching volcanic ash found in polar ice cores to Zavaritski’s ejecta. The eruption had remained undetected for decades due to a lack of eyewitnesses. Moreover, the island’s military status back then further shrouded the evidence. Once a hub for Soviet subs, Brouton Bay, surrounding the easternmost volcano, Uratman, served as a natural harbor for nuclear vessels until the base was abandoned in 1994, as per Live Science.

From southeast to northwest, Simushir’s dramatic profile includes:

1. Milna: The tallest, rising 5,050 feet (1,540 m), last erupted in 1914.

2. Zavaritski: The 1831 climate culprit also erupted in 1957.

3. Prevo: Towering at 4,460 feet (1,360 m), last active in 1825.

4. Uratman: Dormant for over 12,000 years and host to Soviet naval activity.

There’s even a lesser-known fifth volcano, Goriaschaia Sopka, blending into Milna’s northeast flank, barely visible in satellite imagery but geologically distinct, as per Live Science.

Hutchison noted, "We had no idea this volcano was responsible [for the dramatic eruption]... It was completely off the radar," as per Live Science. What makes this discovery iconic is not only the identification of the volcano responsible for a global climate event but also the geopolitical and geologic secrecy surrounding it. Simushir, along with the rest of the Kuril Islands, sits on the volatile Ring of Fire, home to two-thirds of Earth’s active volcanoes and 90% of its earthquakes.