The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.
I rarely write about landslides on other planetary bodies, primarily because this is outside of my comfort zone. However, the European Space Agency (ESA) image below popped up on my feed this morning. It’s so stunning that I couldn’t resist posting it today. This is a Mars Express image of Hebes Chasma:-
According to Wikipedia, a Chasma is a “deep, elongated, steep-sided depression”. Hebes Chasma, which is located close to the Martian equator, is 5 to 6 km deep and 320 km long. In the centre of the Chasma there is a mesa – this can be seen in the image – which is about 5 km high.
The image is dominated by a huge landslide on the centre right, having detached from the outer wall of the Chasma. There are also large landslides from the mesa and slides can be seen on other slopes across the image.
There is a short paper (Kromuszczyńska and Dębniak 2017) in Lunar and Planetary Science on landslides in the Hebes Chasma. I think the main landslide in the image above is their landslide L2. This is one of the larger landslides in the Chasma, but it is not the biggest. There is also some earlier mapping of these landslides using more basic imagery (Quantin et al. 2004). Based on this data, this landslide is 48.3 km long and 31.4 km wide, with a surface area of 966 km2. This is slightly larger than the surface area of New York City (784 km2).
The trigger for these huge failures in Hebes Chasma is postulated as being either high pore fluid pressures or ground shaking. The literature seems to define this type of landslide as being “chaotic”. It is clearly a slump, but the mechanism of movement after failure looks to be quite complex given the jumbled morphology of the deposit.
These giant landslides are intriguing and enigmatic. One really interesting aspect is that the bottom of Hebes Chasma is entirely isolated from the surrounding terrain, so there is no mechanism to allow large-scale export of sediment from the basin. Thus, essentially of the material that was involved in the landslides remains in the basin. This is rarely the case for terrestrial landslides.
Reference
Kromuszczyńska, O. and Dębniak, K.T. 2017. Geomorphological analyses of landslide deposits in Hebes Chasma (Valles Marineres, Mars). Lunar and Planetary Science XLVIII.
Quantin, C. 2004. Morphology and geometry of Valles Marineris landslides.
Planetary and Space Science, 52, 1011-1022.
https://doi.org/10.1016/j.pss.2004.07.016.
Text © 2023. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.
