28 April 2020
Planet Labs high resolution imagery of the Kegesuglo landslide in Papua New Guinea
Yesterday I posted Planet Labs high resolution satellite imagery of the Tendepo landslide in Papua New Guinea. Amazingly, they also captured a high-resolution image of the 10 April 2020 Kegesuglo landslide, which killed 10 people. As I noted at the time:
On Friday 10 April 2020 a large landslide was triggered, probably by rainfall at Kegesuglo in Kundiawa-Gembog district in Papua New Guinea. The location of this landslide appears to be -5.833, 145.1. This is a remote, hilly location at the foot of Mount Wilhelm, the highest mountain in Papua New Guinea. It’s worth noting that in some reports the village is named Keglsugl.
This is a rather different landslide from Tendepo, starting with a smaller failure but transitioning into a channelised debris flow. This is the high-resolution image:-
Many thanks again to my friends at Planet Labs, and in particular to Robert Simmon, for obtaining this wonderful image. It shows the initial failure very clearly in the top left corner,, and then the transition into a channelised flow. The image below provides more detail of the initial failure:-
It is interesting to note that the crown of the landslide appears to be located in an area that retains tree cover. The landslide has started as what in Hong Kong would be termed an open hillslope failure, cutting a broad swathe across the slope. On the right side it intercepts the channel, and transitions onto a channelised flow, as shown below:-
In this phase the landslide has been strongly steered by the existing channel, but in places it has spilled out onto the adjacent terrain. These types of channelised flows are particularly hazardous to people in their path. In many ways this is a smaller version of the massively destructive 2017 Regent landslide in Sierra Leone.
In both of the landslides in Papua New Guinea that I have featured more work is needed to understand why these slides have occurred. These are areas of the country that have undergone significant environmental degradation through the removal of forest cover, but in both cases there is no obvious reason as to why these particular slopes have failed. It is very likely that these areas will suffer further such events; understanding where and when they might occur is important.
Planet Team (2020). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/