Tambora Erupts and Darkens the Following Year

On 5 April 1815, Mount Tambora, a stratovolcano on the island of Sumbawa in modern Indonesia, broke a long dormancy with detonations that soldiers on Java, hundreds of miles away, mistook for cannon fire. Activity intensified dramatically on the evening of 10 April, when three columns of fire shot from the mountain. Pumice rained across the surrounding landscape, violent winds leveled nearby settlements, and pyroclastic flows swept down the peninsula into the sea, destroying local communities including the village of Tambora. Tsunamis generated during the event raced across the Java Sea. The colossal explosion reduced the mountain's summit from approximately 4,300 meters to 2,851 meters, leaving a vast caldera about six kilometers across.

The eruption expelled as much as 150 cubic kilometers of ash, pumice and other rock, earning a rating of 7 on the volcanic explosivity index. Huge floating rafts of pumice trapped ships in harbor, and ash rained down across the region for weeks. The regional human toll was immense. Direct volcanic phenomena killed at least 10,000 individuals, while subsequent agricultural collapse, famine, and disease claimed tens of thousands more on Sumbawa and neighboring Lombok. Estimates of the death toll vary significantly among researchers, ranging from about 71,000 to 121,000 people.