The aberrations are now generally thought to have occurred because of the April 5 – 15 , 1815 , Mount Tambora volcanic eruption on the island of Sumbawa , Indonesia . The eruption had a volcanic explosivity index ( VEI ) ranking of 7 , a colossal event that ejected at least of material . It was the world 's largest eruption since the Hatepe eruption in AD 180
Hatepe eruption
Hatepe eruption
Year Without a Summer