The Year Without A Summer

With the many volcanic eruptions we hear about every day, I find it hard to fathom a statement like “the most powerful volcanic eruption in human history,” but on April 10, 1815, an eruption began in earnest in Indonesia, involving the Tambora volcano. The eruption sent ash 20 miles into the atmosphere and boiling liquified rock streaming down its slopes. The “cacophony of explosions” echoed for hundreds of miles, and within hours, nearby villages vanished, forests were reduced to ash, and massive rivers of lava surged into the sea, reshaping the island’s coastline.

Tambora, located on Sumbawa Island at the eastern edge of the Indonesian archipelago, had shown no volcanic activity for thousands of years before its massive 1815 eruption. Beginning to rumble on April 5, the volcano erupted with such force that it directly killed nearly 100,000 people and indirectly caused tens of millions more deaths worldwide. It was the largest eruption ever recorded, darkening the skies for days as ash blocked out the sun, causing massive local destruction and triggering the global “Year Without a Summer.” The eruption reached its climax on April 10, 1815, producing a Volcanic Explosivity Index (VEI) of 7, ejecting 37–45 km³ of dense-rock equivalent material into the atmosphere. In 1816, the massive amount of ash was characterized by unusually cold temperatures, frosts, and snow during summer months in the Northern Hemisphere. Europe experienced crop failures, food shortages, and famine, while North America saw persistent “dry fog,” frost, and poor harvests. Asia, including China and India, suffered disrupted monsoons, flooding, and famine. The global temperature drop is estimated at 0.7–1 °F on average. Flaming debris hitting the surrounding ocean created steam explosions, and the force of the blast triggered a moderate tsunami. So much rock and ash were expelled that Tambora collapsed into itself, reducing its height from 14,000 feet to 9,000 feet. After the eruption ended, a caldera spanning some 3.7 miles across remained.

The massive explosions were heard hundreds of miles away, prompting rulers to dispatch their armies, convinced a military invasion was imminent. Tambora’s eruptions had a global impact, spewing enough ash into the atmosphere to lower temperatures for the next year and create stunningly colorful sunsets around the world. The eruption was blamed for snow and frost in New England during June and July of that summer. About ten thousand people died directly from the eruptions, most on Sumbawa Island, while in the following months over 80,000 more perished in the surrounding regions from starvation caused by crop failures and disease. A widespread cholera outbreak linked to the eruption claimed countless additional lives.