25 November 2018
Planet Labs SkySat image of the Yarlung Tsangpo valley-blocking landslide
In the last few days Planet Labs have succeeded in capturing a gorgeous SkySat (very high resolution) image of the Yarlung Tsangpo landslide dam. As a reminder, this is a large landslide in Tibet, which originated from a rock and ice avalanche on a glacier. The events has occurred on two occasions in recent weeks, both of which have blocked the valley.
The image is below:-
The location of the breach of the dam is very clear, meaning the the blockage is not impounding a significant amount of water now. Note that there is still a large volume of sediment in the channel though; presumably this will be eroded away in time. This erosion is ongoing – compare the colour of the river water on the upstream and downstream sides of the blockage.
The image provides detail of the chronology of the emplacement of the landslide and of subsequent modification of the landslide mass. It is notable that the landslide spread out both upstream and downstream of the junction with the main channel. Some erosion of the landslide track can now be seen as well. The original landslide mass would have comprised of both ice and sediment; the former will now be thawing, leaving just the mineral matter in the valley.
The reasons for this large glacial landslide remains unclear, but large rockslides and glacial landslides are becoming more common as the climate change crisis rapidly increases rates of melting on glaciers and in permafrost slopes around the world.
Reference and acknowledgement
Thanks to Robert Simmon, Senior Data Visualization Engineer, and his colleagues at Planet Labs for capturing this image and for processing it.
Planet Team (2018). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/