High Quality Content by WIKIPEDIA articles! The 1815 eruption of Mount Tambora was one of the most powerful in recorded history and classified as a VEI-7 event. Mount Tambora is situated on the island of Sumbawa in Indonesia. The eruption began on 10 April was followed by between six months and three years of increased steaming and small phreatic eruptions. The eruption column lowered global temperatures, and some experts believe this led to global cooling and worldwide harvest failures, sometimes known as the Year Without a Summer.