Global Volcanism Program | Image GVP-11748
The small dark-green area below the center of this NASA Landsat image of NW Sumatra (with north to the top) is Imun volcano. This cone of uncertain age lies south of the renowned large caldera containing Lake Toba (top).
NASA Landsat 7 image (worldwind.arc.nasa.gov)
This image is made available as a Public Domain Work, but proper attribution is appreciated.

Imun