16 February 2021
The very large Chunchi landslide in Ecuador
Posted by Dave Petley
The very large Chunchi landslide in Ecuador
Last week a very large landslide occurred near to the town of Chunchi in Ecuador. The scale of the landslide makes this a somewhat unusual event. It was captured on a couple of videos that were posted to Twitter:-
Increíble deslizamiento de gran magnitud en Chunchi, sector la Armenia, Ecuador. A su paso la enorme masa inestable destruye viviendas, tramos de carretera y obstruye el cauce del río. #Landslide #earthflow @davepetley #procesosmorfodinámicos #GestiónDelRiesgoDeDesastres pic.twitter.com/MlI6waa8H9
— Geotweets (@Yobanygf) February 13, 2021
#Chimborazo #Chunchi#Urgente
En el cantón Chunchi se registró un Fuerte deslizamiento de tierra en el sector la Armenia que sepultó a la comunidad de ChanChan .. pic.twitter.com/v2jEBg98t6— ECO DIGITAL (@EcoDigital45) February 12, 2021
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The landslide occurred on 12 February 2021. It is not clear to me at the moment as to the trigger of this enormous landslide, news reports link it to the presence of a fault and to groundwater. The landslide has caused the evacuation of 80 families, and over 500 people, but fortunately did not cause loss of life. Given the very dramatic movements in the video, that is very fortunate.
The scale of the landslide is such that getting a decent image of it is challenging with a drone or satellite imagery. The best picture I have seen is this one:-
The Chunchi landslide in Ecuador. Image by Riesgos via Primicias.
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The upper part of the landslide appears to be a very large rotational failure, which can be seen in the middle right side of the image above. There are some hints that there may be a second source as well, located to the left of the main source – this is on the left side of the image. The main slide appears to have undercut the valley side, causing another substantial area of failure, on the right side of the image (this is the most obvious failure visible).
The failed debris appears to have transformed into a flow with quite high levels of mobility in places, judging by the videos. The consequence is a substantial area of inundated valley.
The biggest threat now appears to be blockage of the channel of the Picay River. Reports indicate that a lake is developing on the upstream side. Efforts are under way to create a channel to avoid an uncontrolled breach.
Many thanks to those people who pointed this one out to me – much appreciated.
Dave Petley is the Vice-Chancellor of the University of Hull in the United Kingdom. His blog provides commentary and analysis of landslide events occurring worldwide, including the landslides themselves, latest research, and conferences and meetings.
Wow. Beside ‘epic’ main event, I noticed collapsing trees on further stream-bank in 1st video’s fore-ground. As bemused observer didn’t turn camera/phone to ‘landscape’, I lost track of them. Did the main flow fully recruit that area, too ? Would trigger have been the local ground-shaking ? ‘Thixotropic R Us’ ??
Thankfully, the local population seems to have ‘dodged a bullet’ this time. Hopefully river channel can be sufficiently cleared to prevent a dire impound-breach…
FWIW, following UK Wales’ coal-waste tip failure a year or two back, BBC TV News reports that survey has found ~300 other ‘legacy’ tips that now represent a significant hazard.
IMHO, lateral adit-style ‘field drains’ may have to be drilled ASAP to prevent rising water-tables driving local spring-line failures or major slumps. Oh, and eluent may be toxic, so treatment plants required…
And, yes, trip-wires & sirens…
Plus, perhaps, a sudden fashion for massive, wedge-shaped ‘garden features’ per alpine avalanche splitters…
Surely there must be strong memories of Aberfan in Wales. I was a child at the time, but I clearly remember being horrified by the news pictures from the other side of the ocean.