Global Volcanism Program | Image GVP-00537
The 35 x 100 km wide Toba caldera, partially filled by Sumatra's Lake Toba, is Earth's largest Quaternary caldera. This view looks W toward the northern end of Samosir Island, which is part of a block that was uplifted after eruption of the Young Toba Tuff (YTT) about 74,000 years ago. The island, once entirely covered by Lake Toba, is formed of caldera-fill deposits of YTT-capped by lake sediments.
Photo by Tom Casadevall, 1987 (U.S. Geological Survey)
This image is made available as a Public Domain Work, but proper attribution is appreciated.