Archive June 2009
Landslides in Ganges Chasma
Lobes from several enormous landslides are visible along the floor of Ganges Chasma.
This image shows a portion of Ganges Chasma, a several kilometers-deep side canyon at the east end of the Valles Marineris canyon system.
Ganges Chasma slices through almost 5 kilometers of the martian crust and reveals ancient rocks and layers in the walls of the canyons that would otherwise be unseen. Lobes from several enormous landslides are visible along the floor of the canyon. Material in a landslide off the north wall of the canyon flowed more than 17 kilometers across the canyon floor, eventually coming to rest atop an older landslide from the south wall, that had travelled nearly as far.
Landslides have very characteristic morphologies on Earth, which they also display on Mars. These morphologies include a distinctive escarpment at the uppermost part of the landslide, called a head scarp, a down-dropped block of material below that escarpment that dropped almost vertically, and a deposit of debris that moved away from the escarpment at high speed.
The image was taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft and has not yet been officially released by ESA.
Image Credit: ESA/DLR/FU Berlin (G. Neukum)/astroarts.org
Perspective view of landslide features
in Ganges Chasma.
Perspective view of Ganges Chasma, looking east.
The vertical exaggeration is 2.
Image Credit: ESA/DLR/FU Berlin (G. Neukum)/astroarts.org
Further reading:
W. J. Burns – Chapter 4: Landslide Features and Their Relative Ages (PDF; 333 KB)
Arsia Mons
Collapse features on the southern flank of
the giant shield volcano Arsia Mons.
This colour composite from infrared, green and blue channel images shows a zone of collapse features on the southern flank of the giant shield volcano Arsia Mons. The total height difference in the land surfaces in this scene is about 7 kilometers, and some individual collapse pits have a depth of more than 2 kilometers. The pits probably formed when lava erupted from the side of Arsia Mons. When lava, or molten rock, finds its way to the surface, it produces several veins and chambers. These slowly empty as the lava erupts and runs down the volcano flanks. Some of the lava reaching the surface cools down and becomes solid, often building a roof over the emptied chamber. The resulting voids collapse due to the weight of the overlying material. At several places, the walls of the pits have been modified by later landslides. The overall trend of the collapse zone runs from the south-west to the north-east, following exactly a giant zone of crustal weakness in the Tharsis region, along which the three large Tharsis volcanoes are aligned. Arsia Mons is the southernmost of these volcanoes. It is 435 kilometers in diameter, almost 20 kilometers high, and the summit caldera is 116 kilometers wide.
The images that were used to create this colour composite were taken on April 2, 2004, by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft. The images were taken from an altitude of 400 kilometers and cover an area of about 80 by 105 kilometers.
The colour composite has not yet been officially released by ESA.
Image Credit: ESA/DLR/FU Berlin (G. Neukum)/astroarts.org
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