Landslides and lava flows at Olympus Mons on Mars

2 May 2013 - Giant landslides, lava flows and tectonic forces are behind this dynamic scene captured recently by ESA's Mars Express of a region scarred by the Solar System's largest volcano, Olympus Mons. The image was taken on 23 January by the spacecraft's high-resolution stereo camera, and focuses on a region known as Sulci Gordii, which lies about 200 km east of Olympus Mons. Sulci Gordii is an 'aureole' deposit - from the Latin for 'circle of light' - and is one of many that form a broken ring around the giant volcano, as hinted at in the context map. The aureoles tell the story of the catastrophic collapse of the lower flanks of Olympus Mons in its distant past. Today, it stands with steep cliff edges that rise 2 km above the surrounding plains. The collapse was brought about by weakening in the rocks supporting the volcanic edifice, perhaps influenced by subsurface water. During the collapse, rocky debris slid down and out over hundreds of kilometres of the surrounding volcanic plains, giving rise to the rough-textured aureole seen today.