The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.
A few days ago I highlighted the severe landslide and GLOF that occurred on the flanks of Vallunaraju in Peru, on 28 April 2025, which caused substantial damage and at least two fatalities. This appears to have been initiated by a landslide on the mountain flanks, triggering a hazard chain that led to the disaster downstream.
Loyal reader Christopher Cluett kindly got in touch. He was climbing on the flanks of the mountain when the chain of events occurred, and has kindly provided both a narrative and some images. I am reproducing these with his permission.
“The weather has not quite stabilized for the season, so over the course of the week we were there, there were heavy afternoon rains. Earlier in the week on 4/23 to acclimatize, we hiked through the valley to Laguna Llaca and back out on the road, so we have some beforehand pictures. Some pictures attached show previous slide activity at the same location. The previous slide was much smaller, as were the rock sizes. The road had been recently repaired from the recent slide in the last few weeks (if I recall correctly) – they installed a drainage tube under the road and backfilled it. When we were hiking out on the road on 4/23, there were 4 people taking soil samples (or running some type of soil testing).
“On 4/27 we hiked up to the Moraine Camp (~4900m). On 4/28 at 2:30 am, we left Moraine Camp for the summit. We heard consistent rockfall all morning while we were approaching the glacier. Then around 3:30 am, when we were transitioning to the glacier, we heard a freight train loud slide. I would assume this was the main event. Our summit route then started to take us away from the main rockfall area, so slide noises diminished. On the way back by the rockfall area, we continued to hear lighter rock fall. There are some pictures of what we think was the main rockfall face (not shown but below this face are two smaller glacier lakes). Our guide suspected the rockfall overflowed the lakes and subsequently created the landslide into the valley.
“You can see in other pictures the road was destroyed. We had to quickly cross it to get out of the valley to meet our transportation. It was evident looking in the valley on the drive out that large boulders showed mud/water markings of very high river levels (maybe 5-6 ft). A lot of the cattle from the valley had congregated on the high part of the road towards the valley entrance.
“It is a bit alarming to see all the slide activity throughout the area. The region is clearly heavily impacted by climate change. If you look at the road to the next valley over, it also has a lot of recently landslide activity.“
These two images show the valley before the day before the 28 April 2025 event:-
This map shows the locations of the images of the landslide:-
These images show the area from which the rockslide originated:-
And these images show the aftermath:-
Many thanks for Christopher for these amazing images.
