In 1831, an unknown volcano erupted so powerfully that it cooled the Earthʼs climate. And now scientists have finally identified it: it is the Zavarytsky volcano on Simushir Island in the Greater Kuril Ridge (Russia).
This is stated in a study published in the journal Proceedings of the National Academy of Sciences.
The eruption of the Zavarytsky volcano, one of the most powerful in the 19th century, released so much sulfur dioxide into the stratosphere that the average annual temperature in the Northern Hemisphere dropped by about 1°C. This occurred in the final years of the Little Ice Age, the coldest period on Earth in the last 10,000 years, which lasted from the early 1400s to about 1850.
The year of the massive eruption was known, but the location of the volcano was not. Researchers have been trying to figure it out for 200 years. Before the current discovery, they took ice cores from Greenland to peer back in time and examine sulfur isotopes, ash grains, and tiny fragments of volcanic glass deposited between 1831 and 1834.
Ice cores.
Using geochemistry, radioactive dating, and computer modeling to map particle trajectories, scientists linked the 1831 eruption to an island volcano in the northwest Pacific Ocean called Zavarytsky. Before that, the last known eruption of Zavarytsky was in 800 BC.
"Zavarytsky Volcano is located on a very remote island between Japan and Russia. No one lives there, and historical records are limited to a few ship logs that passed by these islands once every few years," said lead author of the study, Dr. William Hutchison.
Simushir Island in the northwestern Pacific Ocean.
Researchers considered volcanoes that were closer to the equator, such as Babuyan Claro volcano in the Philippines, as candidates for the 1831 eruption.
"It still amazes me that an eruption of this magnitude has not been reported. Perhaps there is data on ash or atmospheric phenomena that occurred in 1831, stored in a dusty corner of a library in Russia or Japan. Further work on studying these records is very exciting to me," added Hutchison.
Between 1808 and 1835, three more volcanoes erupted along with the Zavarytsky volcano, marking the end of the Little Ice Age, during which annual temperatures in the Northern Hemisphere fell by an average of 0.6°C, and in some places the temperature was 2°C below normal.
Researchers have previously identified two of the four eruptions: Mount Tambora in Indonesia erupted in 1815, and the Coseguin eruption in Nicaragua in 1835. The volcano that erupted in 1808–1809 remains unknown.
After the 1831 eruption, the weather in the Northern Hemisphere was colder and drier. Soon, famines swept through India, Japan, and Europe, affecting millions of people.
Caldera of Zavaritsky volcano.
Like Zavarytsky, many volcanoes around the world are located in isolated, inaccessible locations, making it difficult to predict when and where the next large-scale eruption might occur. However, the 1831 event shows that volcanic activity in remote locations can have devastating global consequences for which people may be unprepared.
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