These studies included detailed field investigations of the historic 1883 eruption of Krakatoa, the 1963 eruption of Mount Agung and the 1815 eruption of Mount Tambora in Indonesia, and their climatic aftermath. The famous “year without a summer” in 1816, during which Mary Shelley was forced to stay indoors to write "Frankenstein", followed the great Tambora eruption. One focus of investigation is the huge “supereruption” (a word coined by Rampino and Self) of Mount Toba (now Lake Toba) in Sumatra ~74,000 years ago. This event may have created a severe “volcanic winter” (another term coined by Rampino) leading to a human population crash predicted from studies of the human genome. Such large eruptions threaten civilization.