Tharsis Tholis towers 8 km above the surrounding terrain with a base that stretches 155 x 125 km and a central caldera measuring 32 x 34 km. The image was created using a Digital Terrain Model (DTM) obtained from the High Resolution Stereo Camera on ESA’s Mars Express spacecraft. Elevation data from the DTM is color-coded: purple indicates the lowest lying regions and beige the highest. The scale is in meters. In these images, the relief has been exaggerated by a factor of three.
Photo credit: ESA/DLR/FU Berlin (G. Neukum)
Note: For more information (and a lot of other, great images), see Battered Tharsis Tholus Volcano on Mars.