Global Volcanism Program | Image GVP-00536
The 35 x 100 km Toba caldera was formed during four powerful explosive eruptions beginning 1.2 million years ago. The latest of these, about 74,000 years ago, was one of the world's largest known Quaternary eruptions, producing the Young Toba Tuff (YTT).
Photo by Tom Casadevall, 1987 (U.S. Geological Survey)
This image is made available as a Public Domain Work, but proper attribution is appreciated.