16 February 2021
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
— VideosDeEcuador (@NotiViralEc) February 12, 2021
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 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.