Perspective view into the caldera at Tharsis Tholus
Perspective view into the caldera at Tharsis Tholus
The main feature of Tharsis Tholus is, however, the size of its central caldera. This slightly elongated collapse crater at the summit of the volcano, measuring roughly 32 by 34 kilometres, extends over an area almost as large as Berlin and the base is as much as 2.7 kilometres below the rim. The caldera may have formed when a shallow magma chamber under the volcano emptied, primarily through volcanic eruptions – during which the magma emerged at the surface in the form of lava. This emptying process caused a large cavity to form inside the volcano. As lava accumulated over this cavity, there came a point when it could no longer support the additional weight and it collapsed, forming a depression known as a ‘collapse caldera’.
Between 28 October and 13 November 2004, the High Resolution Stereo Camera (HRSC) on board Mars Express acquired a series of images during orbits 0997, 1019, 1041 and 1052, which have been combined to form this mosaic image. The colour scheme is based on topographical height values derived from HRSC stereo data.
Copyright note:
As a joint undertaking by DLR, ESA and FU Berlin, the Mars Express HRSC images are published under a Creative Commons licence since December 2014: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO. This licence will also apply to all HRSC images released to date.