17 April 2020
The Salkantay landslide: wonderful Planet Labs high-resolution satellite images
Back in February I wrote a series of pieces reconstructing the events that led to the huge and highly destructive debris flow in the Salkantay region of Peru. It is clear that this event was a large landslide from the mountainside that transitioned into the debris flow. My friends at Planet Labs have now succeeded in capturing not one but two fantastic high-resolution images of the site of the initial landslide. The first was captured on 11 April 2020 using the SkySat instrument:-
The second was captured on 13 April 2020, also using the SkySat instrument:-
Let’s take a closer look at the source of the landslide. An image captured by Benito Moncado of the site shortly after the landslide suggests that the initial failure was a steep wedge high in the rock mass. This is a more detailed view of the landslide scar and the initial downslope deposit:-
It is worth comparing this image with the pre-failure Google Earth image of the Salkantay site:-
Comparison of the two images shows a long section of rock slope that has been removed by the landslide. Interestingly, the 11 April image shows a smaller (but not insignificant) fresh landslide scar near to the crown of the landslide, and a debris trail on the snow, suggesting that some instability is still occurring. The main (February) landslide has planed off the topography down the slope, probably indicating sliding on a joint surface. It is worth noting that this slope is much steeper than it might appear on the satellite image (take a look at the photographs of the site in my earlier post).
I think that the behaviour of the landslide at the foot of the slope is really interesting too, but that is a matter for a future post.
Reference and acknowledgement
Planet Team (2020). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/
Many thanks to Robert Simmon of Planet Labs, and to his colleagues there, for tasking the SkySat instrument and for providing the imagery. Their help and support is hugely appreciated.