14 October 2011
Summary: New NASA imagery of the Vesta asteroid appears to show a very large landslide. The challenge is to find a good terrestrial analogue to this slip.
The NASA Dawn mission is currently imaging using a range of instrumentation to image the Vesta asteroid. A few days ago they released this fascinating image of the South Polar region, showing a huge “mountain” . This feature is 22 km high – about three times the height of Everest. Note the strange topographic features around it, but note also that the image is exaggerated vertically by about 50% and has had the underlying topographic curvature (the same effect as the curvature of the Earth) removed.
Whilst the image itself is really interesting, for me the most fascinating aspect is the tall ridge on the right side, shown enlarged here:
The NASA hypothesise that the deposits at the toe of this scarp, especially on the centre right I suspect, are those from very large landslides. I suspect from the morphology that this is correct. In the image below I have highlighted in black the main block that I would interpret as being a landslide (note the boundaries are indicative at best):
The area that I have high;lighted in red appears to be a small secondary slip in the landslide mass. It is interesting that the very large main landslide complex appears to have slipped but not to have spread in the way that the Saidmareh landslide appears to have:
I have been trying to think of a terrestrial analogue. So far the best I can come up with is the Quiraing on the Isle of Skye, but this is not really a good analogue overall.
There must be much better examples, so over to you. I’ll try to post the best suggestions here over the next few days.