Krakatau

Toba, the Earth's largest Quaternary caldera, is seen here in a false-color satellite image. The 35 x 100 km caldera, partially filled by Lake Toba (see photo above), was formed during four major ignimbrite-forming eruptions in the Pleistocene, the latest of which occurred about 74,000 years ago. The large island of Samosir is a resurgent uplifted block. The solfatarically active Pusukbukit volcano was later constructed near the south-central caldera rim, and Tandukbenua volcano on the NW rim may be only a few hundred years old.