<a href="https://en.wikipedia.org/wiki/Caldera" class="extiw" title="w:Caldera">Caldera</a> of Waw an Namus, an extinct volcano in Libya. A field of dark basaltic ash and tephra extends around the caldera that is about 4 kilometers (2 miles) wide. Within the caldera are three small salty lakes ringed with vegetation. The edge of a <a href="https://en.wikipedia.org/wiki/cinder_cone" class="extiw" title="w:cinder cone">cinder cone</a> is also visible near the center of the caldera.
NASA's Earth Observatory
The <a href="https://en.wikipedia.org/wiki/Operational_Land_Imager" class="extiw" title="w:Operational Land Imager">Operational Land Imager</a> (OLI) on <a href="https://en.wikipedia.org/wiki/Landsat_8" class="extiw" title="w:Landsat 8">Landsat 8</a> (<a rel="nofollow" class="external free" href="http://earthobservatory.nasa.gov/IOTD/view.php?id=86054">http://earthobservatory.nasa.gov/IOTD/view.php?id=86054</a>)