2 May 2015
Gorkha Earthquake – the slowly emerging landslide picture
Posted by Dave Petley
The official name for the earthquake in Nepal a week ago is now the Gorkha Earthquake. The casualty count slowly continues to rise – 6659 fatalities at the latest count, but this is likely to rise significantly in the coming days. We are slowly getting a better understanding of the earthquake and its impacts, although the picture in the rural districts remains worryingly unclear. My sense is that we are now starting to get information about rural settlements on the major highways, but the situation in the many communities away from the main roads (which is the vast majority) remains unclear.
Concentrating on landslides, which is the focus of this blog, I thought I’d pull together some snippets of information that are now available. This is far from comprehensive though.
1. The dreadful damage in the Langtang region
There have been various reports of the impact of landslides in the Langtang region, a popular trekking area, and I wrote about this earlier in the week. Whilst the situation is desperately confused, it appears that there may have been two large rock/ice avalanches, one affecting Langtang itself and the other, a few days later, destroying Ghotabela. Himali Sherpa has posted some images of the destruction in Langtang via Facebook:
It is hard to believe that these will be many survivors from this. It appears that this may have been a rock/ice avalanche, but information is still scarce.
2. ICIMOD analysis of valley blocking landslides
Meanwhile ICIMOD have been leading the analysis of satellite imagery of potential valley-blocking landslides. They have identified a number of large slides, although fortunately to date these do not seem on first inspection to be too problematic. Note though that very large areas remain cloud-covered so we are not out of the woods as yet. The largest to date is in a remote area in the mountains:
3. Landslides on the Arniko Highway
Meanwhile, Kantipur today has an interesting article about efforts to clear the Arniko (sometimes called Araniko) Highway, which is the road that links Kathmandu to Tibet – a vital trade route. It includes this image of landslide damage:
The reports states that:
It is suspected that scores of people, including some foreigners, visiting Tatopani and around 25 vehicles were buried in landslides triggered by Saturday’s massive earthquake. According to witnesses, scores of people were buried at Miteripul, Chaku, Jhyalebhir, Nayapur, Daklang Paharo and Jhirpu. “Ten to fifteen people working at caterings and restaurants in Khasa were buried by landslide at Chaku,” said Shyam Shrestha, who witnessed the tragedy. Some buses, private vehicles and motorcycles were also buried in the area.
Deadly Landslide Triggered by 7.8 Earthquake in Nepal Spotted By Satellite
By Chris Dolce
Published May 3 2015 11:07 AM EDT
The first photo suggests more of a blast wave than burial. There appears to be little actual deposition. This and several other photos from Sherpa’s post show apparent settlement scarps on the far side of the valley. The deposits there resemble baking flour, this of course being from distance, but the mechanism seems similar: lots of air trapped relatively fine material.
It is ironic that many of these towns were built on flats probably created by similar events in the past.