Mount Tambora is a volcanic mountain in Indonesia. It may be hard to imagine how an eruption there could affect the Great Plains, especially from so far away on the other side of the world. But on this date in 1815, it did exactly that. The eruption began on April 5, with small tremors hinting at a major event. Then, on the evening of April 10, a cataclysmic explosion blew the mountain apart. A thick cloud of hot rock fragments and gases, known as a pyroclastic flow, rolled down the mountainside. The explosion and the tsunamis it triggered killed 10,000 people and destroyed 35,000 homes. And that was just the beginning.
Many volcanologists consider Mount Tambora’s eruption the most destructive volcanic event in recorded history. It released as much as 36 cubic miles of ash and pumice into the atmosphere, including an estimated 60 megatons of sulfur. The volcanic cloud spread around the globe, blocking sunlight and causing temperatures to drop by as much as four degrees. That may not sound like much, but as the volcanic material circled the Earth, it led to what became known as the "Year Without a Summer."
The effects of the eruption crossed cultural and national borders—no one was immune. Europe, already struggling with harsh weather disrupting agriculture, continued to face difficulties in 1815. For Americans, the weather stayed relatively normal until 1816, when the cloud reached them. People waiting eagerly for winter to end were shocked when snow continued to fall well into spring—and even summer. The growing season never arrived. The cold weather prevented seeds from being planted, and where seeds were planted, they couldn’t germinate as the ground remained frozen.
This strange weather had an unexpected impact: it spurred Westward Expansion. Many pioneers, believing the weather was limited to the East, surged westward in search of a better life. There were many theories about why summer never came. Some believed it was caused by sunspots, or perhaps a solar eclipse. But no one imagined that the source of their misery was a volcanic mountain on the other side of the world.
Dakota Datebook written by Dr. Carole Butcher
Sources:
- Britannica. “Mount Tambora.” https://www.britannica.com/place/Mount-Tambora Accessed 3/29/2025.
- Climates in Global Cultures and Histories. “The Eruption of Mount Tambora.” https://www.science.smith.edu/climatelit/the-eruption-of-mount-tambora-1815-1818/ Accessed 3/29/2025.
