Mount Tambora produced the enormous 1815 eruption that caused the “Year Without a Summer.” The eruption occurred on Sumbawa in the Dutch East Indies and is commonly classified as a volcanic explosivity index 7 event.
Tambora’s summit collapsed to form a caldera about 6 kilometres wide and roughly 1 kilometre deep. The eruption released vast quantities of ash and sulfur-bearing gases into the stratosphere. These aerosols reduced sunlight and lowered temperatures across parts of the Northern Hemisphere.
The climatic effects were especially severe in 1816. Frosts, snow, crop failures, and food shortages affected parts of Europe and North America, giving that year its famous nickname. The eruption itself also caused enormous local loss of life through ashfall, pyroclastic flows, tsunamis, disease, and famine.
Tambora is still active. A small cone called Doro Api has grown inside the caldera, while the surrounding area is protected as Mount Tambora National Park. Its eruption was larger than Krakatoa’s 1883 eruption by erupted volume.